Contact Dermatitis

Autoeczematization (AE), or id reaction, is a disseminated eczematous reaction that occurs days or weeks after exposure to a primary stimulus, resulting from a release of antigen(s). Whitfield¹ first described AE in 1921, when he postulated that the id reaction was due to sensitization of the skin after a primary stimulus. He called it “a form of auto-intoxication derived from changes in the patient’s own tissues.”¹ The exact prevalence of id reactions is unknown; one study showed that 17% of patients with dermatophyte infections developed an id reaction, typically tinea pedis linked with vesicles on the palms.² Tinea capitis is one of the most common causes of AE in children, which is frequently misdiagnosed as a drug reaction. Approximately 37% of patients diagnosed with stasis dermatitis develop an id reaction (Figure 1). A history of contact dermatitis is common in patients presenting with AE.^2-6

Pathophysiology of Id Reactions

An abnormal immune response against autologous skin antigens may be responsible for the development of AE. Shelley⁵ postulated that hair follicles play an important role in id reactions, as Sharquie et al⁶ recently emphasized for many skin disorders. The pathogenesis of AE is uncertain, but circulating T lymphocytes play a role in this reaction. Normally, T cells are activated by a release of antigens after a primary exposure to a stimulus. However, overactivation of these T cells induces autoimmune reactions such as AE.⁷ Activated T lymphocytes express HLA-DR and IL-2 receptor, markers elevated in the peripheral blood of patients undergoing id reactions. After treatment, the levels of activated T lymphocytes decline. An increase in the number of CD25⁺ T cells and a decrease in the number of suppressor T cells in the blood may occur during an id reaction.^7-9 Keratinocytes produce proinflammatory cytokines, such as thymic stromal erythropoietin, IL-25, and IL-33, that activate T cells.^10-12 Therefore, the most likely pathogenesis of an id reaction is that T lymphocytes are activated at the primary reaction site due to proinflammatory cytokines released by keratinocytes. These activated T cells then travel systemically via hematogenous dissemination. The spread of activated T lymphocytes produces an eczematous reaction at secondary locations distant to the primary site.⁹

Clinical and Histopathological Features of Id Reactions

Clinically, AE is first evident as a vesicular dissemination that groups to form papules or nummular patches and usually is present on the legs, feet, arms, and/or trunk (Figure 2). The primary dermatitis is localized to the area that was the site of contact to the offending stimuli. This localized eczematous eruption begins with an acute or subacute onset. It has the appearance of small crusted vesicles with erythema (Figure 1). The first sign of AE is vesicles presenting near the primary site on flexural surfaces or on the hands and feet. A classic example is tinea pedis linked with vesicles on the palms and sides of the fingers, resembling dyshidrotic eczema. Sites of prior cutaneous trauma, such as dermatoses, scars, and burns, are common locations for early AE. In later stages, vesicles disseminate to the legs, arms, and trunk, where they group to form papules and nummular patches in a symmetrical pattern.^5,13-15 These lesions may be extremely pruritic. The pruritus may be so intense that it interrupts daily activities and disrupts the ability to fall or stay asleep.¹⁶

Histologically, biopsy specimens show psoriasiform spongiotic dermatitis with mononuclear cells contained in the vesicles. Interstitial edema and perivascular lymphohistiocytic infiltrates are evident. Eosinophils also may be present. This pattern is not unique toid reactions.^17-19 Although AE is a reaction pattern that may be due to a fungal or bacterial infection, the etiologic agent is not evident microscopically within the eczema itself.

Etiology of Id Reactions

Id reactions most commonly occur from either stasis dermatitis or tinea pedis, although a wide variety of other causes should be considered. Evaluation of the primary site rather than the id reaction may identify an infectious or parasitic agent. Sometimes the AE reaction is specifically named: dermatophytid with dermatophytosis, bacterid with a bacterial infectious process, and tuberculid with tuberculosis. Similarly, there may be reactions to underlying candidiasis, sporotrichosis, histoplasmosis, and other fungal infections that can cause a cutaneous id reaction.^18,20-22Mycobacterium species, Pseudomonas, Staphylococcus, and Streptococcus are bacterial causes of AE.^15,23-26 Viral infections that can cause an id reaction are herpes simplex virus and molluscum contagiosum.^27-29 Scabies, leishmaniasis, and pediculosis capitis are parasitic infections that may be etiologic.^14,30,31 In addition, noninfectious stimuli besides stasis dermatitis that can produce id reactions include medications, topical creams, tattoo ink, sutures, radiotherapy, and dyshidrotic eczema. The primary reaction to these agents is a localized dermatitis followed by the immunological response that induces a secondary reaction distant from the primary site.^17,18,32-38

Differential Diagnoses

Differential diagnoses include other types of eczema and some vesicular eruptions. Irritant contact dermatitis is another dermatosis that presents as a widespread vesicular eruption due to repetitive exposure to toxic irritants. The rash is erythematous with pustules, blisters, and crusts. It is only found in areas directly exposed to irritants, as opposed to AE, which spreads to areas distant to the primary reaction site. Irritant contact dermatitis presents with more of a burning sensation, whereas AE is more pruritic.^39,40 Allergic contact dermatitis presents with erythematous vesicles and papules and sometimes with bullae. There is edema and crust formation, which often can spread past the point of contact in later stages. Similar to AE, there is intense pruritus. However, allergic contact dermatitis most commonly is caused by exposure to metals, cosmetics, and fragrances, whereas infectious agents and stasis dermatitis are the most common causes of AE.^40,41 It may be challenging to distinguish AE from other causes of widespread eczematous dissemination. Vesicular eruptions sometimes require distinction from AE, including herpetic infections, insect bite reactions, and drug eruptions.^18,42

Treatment

The underlying condition should be treated to mitigate the inflammatory response causing the id reaction. If not skillfully orchestrated, the id reaction can reoccur. For infectious causes of AE, an antifungal, antibacterial, antiviral, or antiparasitic should be given. If stasis dermatitis is responsible for the id reaction, compression stockings and leg elevation are indicated. The id reaction itself is treated with systemic or topical corticosteroids and wet compresses if acute. The goal of these treatments is to reduce patient discomfort caused by the inflammation and pruritus.^18,43

Conclusion

Id reactions are an unusual phenomenon that commonly occurs after fungal skin infections and stasis dermatitis. T lymphocytes and keratinocytes may play a key role in this reaction, with newer research further delineating the process and possibly providing enhanced treatment options. Therapy focuses on treating the underlying condition, supplemented with corticosteroids for the autoeczema.

Autoeczematization (AE), or id reaction, is a disseminated eczematous reaction that occurs days or weeks after exposure to a primary stimulus, resulting from a release of antigen(s). Whitfield¹ first described AE in 1921, when he postulated that the id reaction was due to sensitization of the skin after a primary stimulus. He called it “a form of auto-intoxication derived from changes in the patient’s own tissues.”¹ The exact prevalence of id reactions is unknown; one study showed that 17% of patients with dermatophyte infections developed an id reaction, typically tinea pedis linked with vesicles on the palms.² Tinea capitis is one of the most common causes of AE in children, which is frequently misdiagnosed as a drug reaction. Approximately 37% of patients diagnosed with stasis dermatitis develop an id reaction (Figure 1). A history of contact dermatitis is common in patients presenting with AE.^2-6

Pathophysiology of Id Reactions

An abnormal immune response against autologous skin antigens may be responsible for the development of AE. Shelley⁵ postulated that hair follicles play an important role in id reactions, as Sharquie et al⁶ recently emphasized for many skin disorders. The pathogenesis of AE is uncertain, but circulating T lymphocytes play a role in this reaction. Normally, T cells are activated by a release of antigens after a primary exposure to a stimulus. However, overactivation of these T cells induces autoimmune reactions such as AE.⁷ Activated T lymphocytes express HLA-DR and IL-2 receptor, markers elevated in the peripheral blood of patients undergoing id reactions. After treatment, the levels of activated T lymphocytes decline. An increase in the number of CD25⁺ T cells and a decrease in the number of suppressor T cells in the blood may occur during an id reaction.^7-9 Keratinocytes produce proinflammatory cytokines, such as thymic stromal erythropoietin, IL-25, and IL-33, that activate T cells.^10-12 Therefore, the most likely pathogenesis of an id reaction is that T lymphocytes are activated at the primary reaction site due to proinflammatory cytokines released by keratinocytes. These activated T cells then travel systemically via hematogenous dissemination. The spread of activated T lymphocytes produces an eczematous reaction at secondary locations distant to the primary site.⁹

Clinical and Histopathological Features of Id Reactions

Clinically, AE is first evident as a vesicular dissemination that groups to form papules or nummular patches and usually is present on the legs, feet, arms, and/or trunk (Figure 2). The primary dermatitis is localized to the area that was the site of contact to the offending stimuli. This localized eczematous eruption begins with an acute or subacute onset. It has the appearance of small crusted vesicles with erythema (Figure 1). The first sign of AE is vesicles presenting near the primary site on flexural surfaces or on the hands and feet. A classic example is tinea pedis linked with vesicles on the palms and sides of the fingers, resembling dyshidrotic eczema. Sites of prior cutaneous trauma, such as dermatoses, scars, and burns, are common locations for early AE. In later stages, vesicles disseminate to the legs, arms, and trunk, where they group to form papules and nummular patches in a symmetrical pattern.^5,13-15 These lesions may be extremely pruritic. The pruritus may be so intense that it interrupts daily activities and disrupts the ability to fall or stay asleep.¹⁶

Histologically, biopsy specimens show psoriasiform spongiotic dermatitis with mononuclear cells contained in the vesicles. Interstitial edema and perivascular lymphohistiocytic infiltrates are evident. Eosinophils also may be present. This pattern is not unique toid reactions.^17-19 Although AE is a reaction pattern that may be due to a fungal or bacterial infection, the etiologic agent is not evident microscopically within the eczema itself.

Etiology of Id Reactions

Id reactions most commonly occur from either stasis dermatitis or tinea pedis, although a wide variety of other causes should be considered. Evaluation of the primary site rather than the id reaction may identify an infectious or parasitic agent. Sometimes the AE reaction is specifically named: dermatophytid with dermatophytosis, bacterid with a bacterial infectious process, and tuberculid with tuberculosis. Similarly, there may be reactions to underlying candidiasis, sporotrichosis, histoplasmosis, and other fungal infections that can cause a cutaneous id reaction.^18,20-22Mycobacterium species, Pseudomonas, Staphylococcus, and Streptococcus are bacterial causes of AE.^15,23-26 Viral infections that can cause an id reaction are herpes simplex virus and molluscum contagiosum.^27-29 Scabies, leishmaniasis, and pediculosis capitis are parasitic infections that may be etiologic.^14,30,31 In addition, noninfectious stimuli besides stasis dermatitis that can produce id reactions include medications, topical creams, tattoo ink, sutures, radiotherapy, and dyshidrotic eczema. The primary reaction to these agents is a localized dermatitis followed by the immunological response that induces a secondary reaction distant from the primary site.^17,18,32-38

Differential Diagnoses

Differential diagnoses include other types of eczema and some vesicular eruptions. Irritant contact dermatitis is another dermatosis that presents as a widespread vesicular eruption due to repetitive exposure to toxic irritants. The rash is erythematous with pustules, blisters, and crusts. It is only found in areas directly exposed to irritants, as opposed to AE, which spreads to areas distant to the primary reaction site. Irritant contact dermatitis presents with more of a burning sensation, whereas AE is more pruritic.^39,40 Allergic contact dermatitis presents with erythematous vesicles and papules and sometimes with bullae. There is edema and crust formation, which often can spread past the point of contact in later stages. Similar to AE, there is intense pruritus. However, allergic contact dermatitis most commonly is caused by exposure to metals, cosmetics, and fragrances, whereas infectious agents and stasis dermatitis are the most common causes of AE.^40,41 It may be challenging to distinguish AE from other causes of widespread eczematous dissemination. Vesicular eruptions sometimes require distinction from AE, including herpetic infections, insect bite reactions, and drug eruptions.^18,42

Treatment

The underlying condition should be treated to mitigate the inflammatory response causing the id reaction. If not skillfully orchestrated, the id reaction can reoccur. For infectious causes of AE, an antifungal, antibacterial, antiviral, or antiparasitic should be given. If stasis dermatitis is responsible for the id reaction, compression stockings and leg elevation are indicated. The id reaction itself is treated with systemic or topical corticosteroids and wet compresses if acute. The goal of these treatments is to reduce patient discomfort caused by the inflammation and pruritus.^18,43

Conclusion

Id reactions are an unusual phenomenon that commonly occurs after fungal skin infections and stasis dermatitis. T lymphocytes and keratinocytes may play a key role in this reaction, with newer research further delineating the process and possibly providing enhanced treatment options. Therapy focuses on treating the underlying condition, supplemented with corticosteroids for the autoeczema.

Autoeczematization (AE), or id reaction, is a disseminated eczematous reaction that occurs days or weeks after exposure to a primary stimulus, resulting from a release of antigen(s). Whitfield¹ first described AE in 1921, when he postulated that the id reaction was due to sensitization of the skin after a primary stimulus. He called it “a form of auto-intoxication derived from changes in the patient’s own tissues.”¹ The exact prevalence of id reactions is unknown; one study showed that 17% of patients with dermatophyte infections developed an id reaction, typically tinea pedis linked with vesicles on the palms.² Tinea capitis is one of the most common causes of AE in children, which is frequently misdiagnosed as a drug reaction. Approximately 37% of patients diagnosed with stasis dermatitis develop an id reaction (Figure 1). A history of contact dermatitis is common in patients presenting with AE.^2-6

Pathophysiology of Id Reactions

An abnormal immune response against autologous skin antigens may be responsible for the development of AE. Shelley⁵ postulated that hair follicles play an important role in id reactions, as Sharquie et al⁶ recently emphasized for many skin disorders. The pathogenesis of AE is uncertain, but circulating T lymphocytes play a role in this reaction. Normally, T cells are activated by a release of antigens after a primary exposure to a stimulus. However, overactivation of these T cells induces autoimmune reactions such as AE.⁷ Activated T lymphocytes express HLA-DR and IL-2 receptor, markers elevated in the peripheral blood of patients undergoing id reactions. After treatment, the levels of activated T lymphocytes decline. An increase in the number of CD25⁺ T cells and a decrease in the number of suppressor T cells in the blood may occur during an id reaction.^7-9 Keratinocytes produce proinflammatory cytokines, such as thymic stromal erythropoietin, IL-25, and IL-33, that activate T cells.^10-12 Therefore, the most likely pathogenesis of an id reaction is that T lymphocytes are activated at the primary reaction site due to proinflammatory cytokines released by keratinocytes. These activated T cells then travel systemically via hematogenous dissemination. The spread of activated T lymphocytes produces an eczematous reaction at secondary locations distant to the primary site.⁹

Clinical and Histopathological Features of Id Reactions

Clinically, AE is first evident as a vesicular dissemination that groups to form papules or nummular patches and usually is present on the legs, feet, arms, and/or trunk (Figure 2). The primary dermatitis is localized to the area that was the site of contact to the offending stimuli. This localized eczematous eruption begins with an acute or subacute onset. It has the appearance of small crusted vesicles with erythema (Figure 1). The first sign of AE is vesicles presenting near the primary site on flexural surfaces or on the hands and feet. A classic example is tinea pedis linked with vesicles on the palms and sides of the fingers, resembling dyshidrotic eczema. Sites of prior cutaneous trauma, such as dermatoses, scars, and burns, are common locations for early AE. In later stages, vesicles disseminate to the legs, arms, and trunk, where they group to form papules and nummular patches in a symmetrical pattern.^5,13-15 These lesions may be extremely pruritic. The pruritus may be so intense that it interrupts daily activities and disrupts the ability to fall or stay asleep.¹⁶

Histologically, biopsy specimens show psoriasiform spongiotic dermatitis with mononuclear cells contained in the vesicles. Interstitial edema and perivascular lymphohistiocytic infiltrates are evident. Eosinophils also may be present. This pattern is not unique toid reactions.^17-19 Although AE is a reaction pattern that may be due to a fungal or bacterial infection, the etiologic agent is not evident microscopically within the eczema itself.

Etiology of Id Reactions

Id reactions most commonly occur from either stasis dermatitis or tinea pedis, although a wide variety of other causes should be considered. Evaluation of the primary site rather than the id reaction may identify an infectious or parasitic agent. Sometimes the AE reaction is specifically named: dermatophytid with dermatophytosis, bacterid with a bacterial infectious process, and tuberculid with tuberculosis. Similarly, there may be reactions to underlying candidiasis, sporotrichosis, histoplasmosis, and other fungal infections that can cause a cutaneous id reaction.^18,20-22Mycobacterium species, Pseudomonas, Staphylococcus, and Streptococcus are bacterial causes of AE.^15,23-26 Viral infections that can cause an id reaction are herpes simplex virus and molluscum contagiosum.^27-29 Scabies, leishmaniasis, and pediculosis capitis are parasitic infections that may be etiologic.^14,30,31 In addition, noninfectious stimuli besides stasis dermatitis that can produce id reactions include medications, topical creams, tattoo ink, sutures, radiotherapy, and dyshidrotic eczema. The primary reaction to these agents is a localized dermatitis followed by the immunological response that induces a secondary reaction distant from the primary site.^17,18,32-38

Differential Diagnoses

Differential diagnoses include other types of eczema and some vesicular eruptions. Irritant contact dermatitis is another dermatosis that presents as a widespread vesicular eruption due to repetitive exposure to toxic irritants. The rash is erythematous with pustules, blisters, and crusts. It is only found in areas directly exposed to irritants, as opposed to AE, which spreads to areas distant to the primary reaction site. Irritant contact dermatitis presents with more of a burning sensation, whereas AE is more pruritic.^39,40 Allergic contact dermatitis presents with erythematous vesicles and papules and sometimes with bullae. There is edema and crust formation, which often can spread past the point of contact in later stages. Similar to AE, there is intense pruritus. However, allergic contact dermatitis most commonly is caused by exposure to metals, cosmetics, and fragrances, whereas infectious agents and stasis dermatitis are the most common causes of AE.^40,41 It may be challenging to distinguish AE from other causes of widespread eczematous dissemination. Vesicular eruptions sometimes require distinction from AE, including herpetic infections, insect bite reactions, and drug eruptions.^18,42

Treatment

The underlying condition should be treated to mitigate the inflammatory response causing the id reaction. If not skillfully orchestrated, the id reaction can reoccur. For infectious causes of AE, an antifungal, antibacterial, antiviral, or antiparasitic should be given. If stasis dermatitis is responsible for the id reaction, compression stockings and leg elevation are indicated. The id reaction itself is treated with systemic or topical corticosteroids and wet compresses if acute. The goal of these treatments is to reduce patient discomfort caused by the inflammation and pruritus.^18,43

Conclusion

Id reactions are an unusual phenomenon that commonly occurs after fungal skin infections and stasis dermatitis. T lymphocytes and keratinocytes may play a key role in this reaction, with newer research further delineating the process and possibly providing enhanced treatment options. Therapy focuses on treating the underlying condition, supplemented with corticosteroids for the autoeczema.

Plants can contribute to a variety of dermatoses. The Toxicodendron genus, which includes poison ivy, poison oak, and poison sumac, is a well-known and common cause of allergic contact dermatitis (ACD), but many other plants can cause direct or airborne contact dermatitis, especially in gardeners, florists, and farmers. This article provides an overview of different plant-related dermatoses and culprit plants as well as how these dermatoses should be diagnosed and treated.

Epidemiology

Plant dermatoses affect more than 50 million individuals each year.^1,2 In the United States, the Toxicodendron genus causes ACD in more than 70% of exposed individuals, leading to medical visits.³ An urgent care visit for a plant-related dermatitis is estimated to cost $168, while an emergency department visit can cost 3 times as much.⁴ Although less common, Compositae plants are another important culprit of plant dermatitis, particularly in gardeners, florists, and farmers. Data from the 2017-2018 North American Contact Dermatitis Group screening series (N=4947) showed sesquiterpene lactones and Compositae to be positive in 0.5% of patch-tested patients.⁵

Plant Dermatitis Classifications

Plant dermatitis can be classified into 5 main categories: ACD, mechanical irritant contact dermatitis, chemical irritant contact dermatitis, light-mediated dermatitis, and pseudophytodermatitis.⁶

Allergic contact dermatitis is an immune-mediated type IV delayed hypersensitivity reaction. The common molecular allergens in plants include phenols, α-methylene-γ-butyrolactones, quinones, terpenes, disulfides, isothiocyanates, and polyacetylenic derivatives.⁶

Plant contact dermatitis due to mechanical and chemical irritants is precipitated by multiple mechanisms, including disruption of the epidermal barrier and subsequent cytokine release from keratinocytes.⁷ Nonimmunologic contact urticaria from plants is thought to be a type of irritant reaction precipitated by mechanical or chemical trauma.⁸

Light-mediated dermatitis includes phytophotodermatitis and photoallergic contact dermatitis. Phytophotodermatitis is a phototoxic reaction triggered by exposure to both plant-derived furanocoumarin and UVA light.⁹ By contrast, photoallergic contact dermatitis is a delayed hypersensitivity reaction from prior sensitization to a light-activated antigen.¹⁰

Pseudophytodermatitis, as its name implies, is not truly mediated by an allergen or irritant intrinsic to the plant but rather by dyes, waxes, insecticides, or arthropods that inhabit the plant or are secondarily applied.⁶

Common Plant Allergens

Anacardiaceae Family
Most of the allergenic plants within the Anacardiaceae family belong to the Toxicodendron genus, which encompasses poison ivy (Toxicodendron radicans), poison oak (Toxicodendron pubescens,Toxicodendron quercifolium, Toxicodendron diversiloum), and poison sumac (Toxicodendron vernix). Poison ivy is the celebrity of the Anacardiaceae family and contributes to most cases of plant-related ACD. It is found in every state in the continental United States. Poison oak is another common culprit found in the western and southeastern United States.¹¹ Plants within the Anacardiaceae family contain an oleoresin called urushiol, which is the primary sensitizing substance. Although poison ivy and poison oak grow well in full sun to partial shade, poison sumac typically is found in damp swampy areas east of the Rocky Mountains. Most cases of ACD related to Anacardiaceae species are due to direct contact with urushiol from a Toxicodendron plant, but burning of brush containing Toxicodendron can cause airborne exposure when urushiol oil is carried by smoke particles.¹² Sensitization to Toxicodendron can cause ACD to other Anacardiaceae species such as the Japanese lacquer tree (Toxicodendron vernicifluum), mango tree (Mangifera indica), cashew tree (Anacardium occidentale), and Indian marking nut tree (Semecarpus anacardium).⁶ Cross-reactions to components of the ginkgo tree (Ginkgo biloba) also are possible.

Toxicodendron plants can be more easily identified and avoided with knowledge of their characteristic leaf patterns. The most dependable way to identify poison ivy and poison oak species is to look for plants with 3 leaves, giving rise to the common saying, “Leaves of three, leave them be.” Poison sumac plants have groups of 7 to 13 leaves arranged as pairs along a central rib. Another helpful finding is a black deposit that Toxicodendron species leave behind following trauma to the leaves. Urushiol oxidizes when exposed to air and turns into a black deposit that can be seen on damaged leaves themselves or can be demonstrated in a black spot test to verify if a plant is a Toxicodendron species. The test is performed by gathering (carefully, without direct contact) a few leaves in a paper towel and crushing them to release sap. Within minutes, the sap will turn black if the plant is indeed a Toxicodendron species.¹³Pruritic, edematous, erythematous papules, plaques, and eventual vesicles in a linear distribution are suspicious for Toxicodendron exposure. Although your pet will not develop Toxicodendron ACD, oleoresin-contaminated pets can transfer the oils to their owners after coming into contact with these plants. Toxicodendron dermatitis also can be acquired from oleoresin-contaminated fomites such as clothing and shoes worn in the garden or when hiking. Toxicodendron dermatitis can appear at different sites on the body at different times depending on the amount of oleoresin exposure as well as epidermal thickness. For example, the oleoresin can be transferred from the hands to body areas with a thinner stratum corneum (eg, genitalia) and cause subsequent dermatitis.¹

Compositae Family
The Compositae family (also known as Asteraceae) is a large plant family with more than 20,000 species, including numerous weeds, wildflowers, and vegetables. The flowers, leaves, stems, and pollens of the Compositae family are coated by cyclic esters called sesquiterpene lactones. Mitchell and Dupuis¹⁴ showed that sesquiterpene lactones are the allergens responsible for ACD to various Compositae plants, including ragweed (Ambrosia), sneezeweed (Helenium), and chrysanthemums (Chrysanthemum). Common Compositae vegetables such as lettuce (Lactuca sativa) have been reported to cause ACD in chefs, grocery store produce handlers, gardeners, and even owners of lettuce-eating pet guinea pigs and turtles.¹⁵ Similarly, artichokes (Cynara scolymus) can cause ACD in gardeners.¹⁶ Exposure to Compositae species also has been implicated in photoallergic reactions, and studies have demonstrated that some patients with chronic actinic dermatitis also have positive patch test reactions to Compositae species and/or sesquiterpene lactones.^17,18

In addition to direct contact with Compositae plants, airborne exposure to sesquiterpene lactones can cause ACD.¹⁴ The pattern of airborne contact dermatitis typically involves exposed areas such as the eyelids, central face, and/or neck. The beak sign also can be a clue to airborne contact dermatitis, which involves dermatitis of the face that spares the nasal tip and/or nasal ridge. It is thought that the beak sign may result from increased sebaceous gland concentration on the nose, which prevents penetration of allergens and irritants.¹⁹ Unlike photoallergic contact dermatitis, which also can involve the face, airborne ACD frequently involves photoprotected areas such as the submandibular chin and the upper lip. Davies and Kersey²⁰ reported the case of a groundsman who was cutting grass with dandelions (Taraxacum officinale) and was found to have associated airborne ACD of the face, neck, and forearms due to Compositae allergy. In a different setting, the aromas of chamomile (Matricaria chamomilla) have been reported to cause airborne ACD in a tea drinker.²¹ Paulsen²² found that ingestion of chamomile tea can induce systemic ACD in sensitized individuals.

Alstroemeriaceae, Liliaceae, and Primulaceae
Florists are exposed to many plant species and have a high prevalence of ACD. Thiboutot et al²³ found that 15 of 57 (26%) floral workers experienced hand dermatitis that cleared with time away from work. The Peruvian lily (Alstroemeria, Alstroemeriaceae family), which contains tuliposide A, was found to be the leading cause of sensitization.²³ Tulips (Tulipa, Liliaceae family), as the flower name suggests, also contain tuliposide A, which along with mechanical irritation from the course tecta fibers on the bulbs lead to a dermatitis known as tulip fingers.^24,25 Poison primrose (Primula obconica, Primulaceae family), cultivated for its highly colorful flowers, contains the contact allergen primin.⁶ A common clinical presentation of ACD for any of these culprit flowers is localized dermatitis of the thumb and index finger in a florist or gardener.

Plants That Cause Irritant Reactions

Cactuses
Although the long spines of the Cactaceae family of cactuses is a warning for passersby, it is the small and nearly invisible barbed hairs (glochids) that inflict a more dramatic cutaneous reaction. The prickly pear cactus (Opuntia species) is a good example of such a plant, as its glochids cause mechanical irritation but also can become embedded in the skin and result in subcutaneous granulomas known as sabra dermatitis.²⁶

Stinging Nettle
The dermatologic term urticaria owes its namesake to the stinging nettle plant, which comes from the family Urticaceae. The stinging nettle has small hairs on its leaves, referred to as stinging trichomes, which have needlelike tips that pierce the skin and inject a mix of histamine, formic acid, and acetylcholine, causing a pruritic dermatitis that may last up to 12 hours.²⁷ The plant is found worldwide and is a common weed in North America.

Phytophotodermatitis

Lemons and limes (Rutaceae family) are common culprits of phytophotodermatitis, often causing what is known as a margarita burn after outdoor consumption or preparation of this tasty citrus beverage.²⁸ An accidental spray of lime juice on the skin while adding it to a beer, guacamole, salsa, or any other food or beverage also can cause phytophotodermatitis.^29-31 Although the juice of lemons and limes contains psoralens, the rind can contain a 6- to 186-fold increased concentration.³² Psoralen is the photoactive agent in Rutaceae plants that intercalates in double-stranded DNA and promotes intrastrand cross-links when exposed to UVA light, which ultimately leads to dermatitis.⁹ Phytophotodermatitis commonly causes erythema, edema, and painful bullae on sun-exposed areas and classically heals with hyperpigmentation.

Pseudophytodermatitis can occur in grain farmers and harvesters who handle wheat and/or barley and incidentally come in contact with insects and chemicals on the plant material. Pseudophytodermatitis from mites in the wheat and/or barley plant can occur at harvest time when contact with the plant material is high. Insects such as the North American itch mite (Pediculoides ventricosus) can cause petechiae, wheals, and pustules. In addition, insecticides such as malathion and arsenical sprays that are applied to plant leaves can cause pseudophytodermatitis, which may be initially diagnosed as dermatitis to the plant itself.⁶

Patch Testing to Plants

When a patient presents with recurrent or persistent dermatitis and a plant contact allergen is suspected, patch testing is indicated. Most comprehensive patch test series contain various plant allergens, such as sesquiterpene lactones, Compositae mix, and limonene hydroperoxides, and patch testing to a specialized plant series may be necessary. Poison ivy/oak/sumac allergens typically are not included in patch test series because of the high prevalence of allergic reactions to these chemicals and the likelihood of sensitization when patch testing with urushiol. Compositae contact sensitization can be difficult to diagnose because neither sesquiterpene lactone mix 0.1% nor parthenolide 0.1% are sensitive enough to pick up all Compositae allergies.^33,34 Paulsen and Andersen³⁴ proposed that if Compositae sensitization is suspected, testing should include sesquiterpene lactone, parthenolide, and Compositae mix II 2.5%, as well as other potential Compositae allergens based on the patient’s history.³⁴

Because plants can have geographic variability and contain potentially unknown allergens,³⁵ testing to plant components may increase the diagnostic yield of patch testing. Dividing the plant into component parts (ie, stem, bulb, leaf, flower) is helpful, as different components have different allergen concentrations. It is important to consult expert resources before proceeding with plant component patch testing because irritant reactions are frequent and may confound the testing.³⁶

Prevention and Treatment

For all plant dermatoses, the mainstay of prevention is to avoid contact with the offending plant material. Gloves can be an important protective tool for plant dermatitis prevention; the correct material depends on the plant species being handled. Rubber gloves should not be worn to protect against Toxicodendron plants since the catechols in urushiol are soluble in rubber; vinyl gloves should be worn instead.⁶ Marks³⁷ found that tuliposide A, the allergen in the Peruvian lily (Alstroemeria), penetrates both vinyl and latex gloves; it does not penetrate nitrile gloves. If exposed, the risk of dermatitis can be decreased if the allergen is washed away with soap and water as soon as possible. Some allergens such as Toxicodendron are absorbed quickly and need to be washed off within 10 minutes of exposure.⁶ Importantly, exposed gardening gloves may continue to perpetuate ACD if the allergen is not also washed off the gloves themselves.

For light-mediated dermatoses, sun avoidance or use of an effective sunscreen can reduce symptoms in an individual who has already been exposed.¹⁰ UVA light activates psoralen-mediated dermatitis but not until 30 to 120 minutes after absorption into the skin.³⁸

Barrier creams are thought to be protective against plant ACD through a variety of mechanisms. The cream itself is meant to reduce skin contact to an allergen or irritant. Additionally, barrier creams contain active ingredients such as silicone, hydrocarbons, and aluminum chlorohydrate, which are thought to trap or transform offending agents before contacting the skin. When contact with a Toxicodendron species is anticipated, Marks et al³⁹ found that dermatitis was absent or significantly reduced when 144 patients were pretreated with quaternium-18 bentonite lotion 5% (P<.0001).

Although allergen avoidance and use of gloves and barrier creams are the mainstays of preventing plant dermatoses, treatment often is required to control postexposure symptoms. For all plant dermatoses, topical corticosteroids can be used to reduce inflammation and pruritus. In some cases, systemic steroids may be necessary. To prevent rebound of dermatitis, patients often require a 3-week or longer course of oral steroids to quell the reaction, particularly if the dermatitis is vigorous or an id reaction is present.⁴⁰ Antihistamines and cold compresses also can provide symptomatic relief.

Final Interpretation

Plants can cause a variety of dermatoses. Although Toxicodendron plants are the most frequent cause of ACD, it is important to keep in mind that florists, gardeners, and farmers are exposed to a large variety of allergens, irritants, and phototoxic agents that cause dermatoses as well. Confirmation of plant-induced ACD involves patch testing against suspected species. Prevention involves use of appropriate barriers and avoidance of implicated plants. Treatment includes topical steroids, antihistamines, and prednisone.

Plants can contribute to a variety of dermatoses. The Toxicodendron genus, which includes poison ivy, poison oak, and poison sumac, is a well-known and common cause of allergic contact dermatitis (ACD), but many other plants can cause direct or airborne contact dermatitis, especially in gardeners, florists, and farmers. This article provides an overview of different plant-related dermatoses and culprit plants as well as how these dermatoses should be diagnosed and treated.

Epidemiology

Plant dermatoses affect more than 50 million individuals each year.^1,2 In the United States, the Toxicodendron genus causes ACD in more than 70% of exposed individuals, leading to medical visits.³ An urgent care visit for a plant-related dermatitis is estimated to cost $168, while an emergency department visit can cost 3 times as much.⁴ Although less common, Compositae plants are another important culprit of plant dermatitis, particularly in gardeners, florists, and farmers. Data from the 2017-2018 North American Contact Dermatitis Group screening series (N=4947) showed sesquiterpene lactones and Compositae to be positive in 0.5% of patch-tested patients.⁵

Plant Dermatitis Classifications

Plant dermatitis can be classified into 5 main categories: ACD, mechanical irritant contact dermatitis, chemical irritant contact dermatitis, light-mediated dermatitis, and pseudophytodermatitis.⁶

Allergic contact dermatitis is an immune-mediated type IV delayed hypersensitivity reaction. The common molecular allergens in plants include phenols, α-methylene-γ-butyrolactones, quinones, terpenes, disulfides, isothiocyanates, and polyacetylenic derivatives.⁶

Plant contact dermatitis due to mechanical and chemical irritants is precipitated by multiple mechanisms, including disruption of the epidermal barrier and subsequent cytokine release from keratinocytes.⁷ Nonimmunologic contact urticaria from plants is thought to be a type of irritant reaction precipitated by mechanical or chemical trauma.⁸

Light-mediated dermatitis includes phytophotodermatitis and photoallergic contact dermatitis. Phytophotodermatitis is a phototoxic reaction triggered by exposure to both plant-derived furanocoumarin and UVA light.⁹ By contrast, photoallergic contact dermatitis is a delayed hypersensitivity reaction from prior sensitization to a light-activated antigen.¹⁰

Pseudophytodermatitis, as its name implies, is not truly mediated by an allergen or irritant intrinsic to the plant but rather by dyes, waxes, insecticides, or arthropods that inhabit the plant or are secondarily applied.⁶

Common Plant Allergens

Anacardiaceae Family
Most of the allergenic plants within the Anacardiaceae family belong to the Toxicodendron genus, which encompasses poison ivy (Toxicodendron radicans), poison oak (Toxicodendron pubescens,Toxicodendron quercifolium, Toxicodendron diversiloum), and poison sumac (Toxicodendron vernix). Poison ivy is the celebrity of the Anacardiaceae family and contributes to most cases of plant-related ACD. It is found in every state in the continental United States. Poison oak is another common culprit found in the western and southeastern United States.¹¹ Plants within the Anacardiaceae family contain an oleoresin called urushiol, which is the primary sensitizing substance. Although poison ivy and poison oak grow well in full sun to partial shade, poison sumac typically is found in damp swampy areas east of the Rocky Mountains. Most cases of ACD related to Anacardiaceae species are due to direct contact with urushiol from a Toxicodendron plant, but burning of brush containing Toxicodendron can cause airborne exposure when urushiol oil is carried by smoke particles.¹² Sensitization to Toxicodendron can cause ACD to other Anacardiaceae species such as the Japanese lacquer tree (Toxicodendron vernicifluum), mango tree (Mangifera indica), cashew tree (Anacardium occidentale), and Indian marking nut tree (Semecarpus anacardium).⁶ Cross-reactions to components of the ginkgo tree (Ginkgo biloba) also are possible.

Toxicodendron plants can be more easily identified and avoided with knowledge of their characteristic leaf patterns. The most dependable way to identify poison ivy and poison oak species is to look for plants with 3 leaves, giving rise to the common saying, “Leaves of three, leave them be.” Poison sumac plants have groups of 7 to 13 leaves arranged as pairs along a central rib. Another helpful finding is a black deposit that Toxicodendron species leave behind following trauma to the leaves. Urushiol oxidizes when exposed to air and turns into a black deposit that can be seen on damaged leaves themselves or can be demonstrated in a black spot test to verify if a plant is a Toxicodendron species. The test is performed by gathering (carefully, without direct contact) a few leaves in a paper towel and crushing them to release sap. Within minutes, the sap will turn black if the plant is indeed a Toxicodendron species.¹³Pruritic, edematous, erythematous papules, plaques, and eventual vesicles in a linear distribution are suspicious for Toxicodendron exposure. Although your pet will not develop Toxicodendron ACD, oleoresin-contaminated pets can transfer the oils to their owners after coming into contact with these plants. Toxicodendron dermatitis also can be acquired from oleoresin-contaminated fomites such as clothing and shoes worn in the garden or when hiking. Toxicodendron dermatitis can appear at different sites on the body at different times depending on the amount of oleoresin exposure as well as epidermal thickness. For example, the oleoresin can be transferred from the hands to body areas with a thinner stratum corneum (eg, genitalia) and cause subsequent dermatitis.¹

Compositae Family
The Compositae family (also known as Asteraceae) is a large plant family with more than 20,000 species, including numerous weeds, wildflowers, and vegetables. The flowers, leaves, stems, and pollens of the Compositae family are coated by cyclic esters called sesquiterpene lactones. Mitchell and Dupuis¹⁴ showed that sesquiterpene lactones are the allergens responsible for ACD to various Compositae plants, including ragweed (Ambrosia), sneezeweed (Helenium), and chrysanthemums (Chrysanthemum). Common Compositae vegetables such as lettuce (Lactuca sativa) have been reported to cause ACD in chefs, grocery store produce handlers, gardeners, and even owners of lettuce-eating pet guinea pigs and turtles.¹⁵ Similarly, artichokes (Cynara scolymus) can cause ACD in gardeners.¹⁶ Exposure to Compositae species also has been implicated in photoallergic reactions, and studies have demonstrated that some patients with chronic actinic dermatitis also have positive patch test reactions to Compositae species and/or sesquiterpene lactones.^17,18

In addition to direct contact with Compositae plants, airborne exposure to sesquiterpene lactones can cause ACD.¹⁴ The pattern of airborne contact dermatitis typically involves exposed areas such as the eyelids, central face, and/or neck. The beak sign also can be a clue to airborne contact dermatitis, which involves dermatitis of the face that spares the nasal tip and/or nasal ridge. It is thought that the beak sign may result from increased sebaceous gland concentration on the nose, which prevents penetration of allergens and irritants.¹⁹ Unlike photoallergic contact dermatitis, which also can involve the face, airborne ACD frequently involves photoprotected areas such as the submandibular chin and the upper lip. Davies and Kersey²⁰ reported the case of a groundsman who was cutting grass with dandelions (Taraxacum officinale) and was found to have associated airborne ACD of the face, neck, and forearms due to Compositae allergy. In a different setting, the aromas of chamomile (Matricaria chamomilla) have been reported to cause airborne ACD in a tea drinker.²¹ Paulsen²² found that ingestion of chamomile tea can induce systemic ACD in sensitized individuals.

Alstroemeriaceae, Liliaceae, and Primulaceae
Florists are exposed to many plant species and have a high prevalence of ACD. Thiboutot et al²³ found that 15 of 57 (26%) floral workers experienced hand dermatitis that cleared with time away from work. The Peruvian lily (Alstroemeria, Alstroemeriaceae family), which contains tuliposide A, was found to be the leading cause of sensitization.²³ Tulips (Tulipa, Liliaceae family), as the flower name suggests, also contain tuliposide A, which along with mechanical irritation from the course tecta fibers on the bulbs lead to a dermatitis known as tulip fingers.^24,25 Poison primrose (Primula obconica, Primulaceae family), cultivated for its highly colorful flowers, contains the contact allergen primin.⁶ A common clinical presentation of ACD for any of these culprit flowers is localized dermatitis of the thumb and index finger in a florist or gardener.

Plants That Cause Irritant Reactions

Cactuses
Although the long spines of the Cactaceae family of cactuses is a warning for passersby, it is the small and nearly invisible barbed hairs (glochids) that inflict a more dramatic cutaneous reaction. The prickly pear cactus (Opuntia species) is a good example of such a plant, as its glochids cause mechanical irritation but also can become embedded in the skin and result in subcutaneous granulomas known as sabra dermatitis.²⁶

Stinging Nettle
The dermatologic term urticaria owes its namesake to the stinging nettle plant, which comes from the family Urticaceae. The stinging nettle has small hairs on its leaves, referred to as stinging trichomes, which have needlelike tips that pierce the skin and inject a mix of histamine, formic acid, and acetylcholine, causing a pruritic dermatitis that may last up to 12 hours.²⁷ The plant is found worldwide and is a common weed in North America.

Phytophotodermatitis

Lemons and limes (Rutaceae family) are common culprits of phytophotodermatitis, often causing what is known as a margarita burn after outdoor consumption or preparation of this tasty citrus beverage.²⁸ An accidental spray of lime juice on the skin while adding it to a beer, guacamole, salsa, or any other food or beverage also can cause phytophotodermatitis.^29-31 Although the juice of lemons and limes contains psoralens, the rind can contain a 6- to 186-fold increased concentration.³² Psoralen is the photoactive agent in Rutaceae plants that intercalates in double-stranded DNA and promotes intrastrand cross-links when exposed to UVA light, which ultimately leads to dermatitis.⁹ Phytophotodermatitis commonly causes erythema, edema, and painful bullae on sun-exposed areas and classically heals with hyperpigmentation.

Pseudophytodermatitis can occur in grain farmers and harvesters who handle wheat and/or barley and incidentally come in contact with insects and chemicals on the plant material. Pseudophytodermatitis from mites in the wheat and/or barley plant can occur at harvest time when contact with the plant material is high. Insects such as the North American itch mite (Pediculoides ventricosus) can cause petechiae, wheals, and pustules. In addition, insecticides such as malathion and arsenical sprays that are applied to plant leaves can cause pseudophytodermatitis, which may be initially diagnosed as dermatitis to the plant itself.⁶

Patch Testing to Plants

When a patient presents with recurrent or persistent dermatitis and a plant contact allergen is suspected, patch testing is indicated. Most comprehensive patch test series contain various plant allergens, such as sesquiterpene lactones, Compositae mix, and limonene hydroperoxides, and patch testing to a specialized plant series may be necessary. Poison ivy/oak/sumac allergens typically are not included in patch test series because of the high prevalence of allergic reactions to these chemicals and the likelihood of sensitization when patch testing with urushiol. Compositae contact sensitization can be difficult to diagnose because neither sesquiterpene lactone mix 0.1% nor parthenolide 0.1% are sensitive enough to pick up all Compositae allergies.^33,34 Paulsen and Andersen³⁴ proposed that if Compositae sensitization is suspected, testing should include sesquiterpene lactone, parthenolide, and Compositae mix II 2.5%, as well as other potential Compositae allergens based on the patient’s history.³⁴

Because plants can have geographic variability and contain potentially unknown allergens,³⁵ testing to plant components may increase the diagnostic yield of patch testing. Dividing the plant into component parts (ie, stem, bulb, leaf, flower) is helpful, as different components have different allergen concentrations. It is important to consult expert resources before proceeding with plant component patch testing because irritant reactions are frequent and may confound the testing.³⁶

Prevention and Treatment

For all plant dermatoses, the mainstay of prevention is to avoid contact with the offending plant material. Gloves can be an important protective tool for plant dermatitis prevention; the correct material depends on the plant species being handled. Rubber gloves should not be worn to protect against Toxicodendron plants since the catechols in urushiol are soluble in rubber; vinyl gloves should be worn instead.⁶ Marks³⁷ found that tuliposide A, the allergen in the Peruvian lily (Alstroemeria), penetrates both vinyl and latex gloves; it does not penetrate nitrile gloves. If exposed, the risk of dermatitis can be decreased if the allergen is washed away with soap and water as soon as possible. Some allergens such as Toxicodendron are absorbed quickly and need to be washed off within 10 minutes of exposure.⁶ Importantly, exposed gardening gloves may continue to perpetuate ACD if the allergen is not also washed off the gloves themselves.

For light-mediated dermatoses, sun avoidance or use of an effective sunscreen can reduce symptoms in an individual who has already been exposed.¹⁰ UVA light activates psoralen-mediated dermatitis but not until 30 to 120 minutes after absorption into the skin.³⁸

Barrier creams are thought to be protective against plant ACD through a variety of mechanisms. The cream itself is meant to reduce skin contact to an allergen or irritant. Additionally, barrier creams contain active ingredients such as silicone, hydrocarbons, and aluminum chlorohydrate, which are thought to trap or transform offending agents before contacting the skin. When contact with a Toxicodendron species is anticipated, Marks et al³⁹ found that dermatitis was absent or significantly reduced when 144 patients were pretreated with quaternium-18 bentonite lotion 5% (P<.0001).

Although allergen avoidance and use of gloves and barrier creams are the mainstays of preventing plant dermatoses, treatment often is required to control postexposure symptoms. For all plant dermatoses, topical corticosteroids can be used to reduce inflammation and pruritus. In some cases, systemic steroids may be necessary. To prevent rebound of dermatitis, patients often require a 3-week or longer course of oral steroids to quell the reaction, particularly if the dermatitis is vigorous or an id reaction is present.⁴⁰ Antihistamines and cold compresses also can provide symptomatic relief.

Final Interpretation

Plants can cause a variety of dermatoses. Although Toxicodendron plants are the most frequent cause of ACD, it is important to keep in mind that florists, gardeners, and farmers are exposed to a large variety of allergens, irritants, and phototoxic agents that cause dermatoses as well. Confirmation of plant-induced ACD involves patch testing against suspected species. Prevention involves use of appropriate barriers and avoidance of implicated plants. Treatment includes topical steroids, antihistamines, and prednisone.

Plants can contribute to a variety of dermatoses. The Toxicodendron genus, which includes poison ivy, poison oak, and poison sumac, is a well-known and common cause of allergic contact dermatitis (ACD), but many other plants can cause direct or airborne contact dermatitis, especially in gardeners, florists, and farmers. This article provides an overview of different plant-related dermatoses and culprit plants as well as how these dermatoses should be diagnosed and treated.

Epidemiology

Plant dermatoses affect more than 50 million individuals each year.^1,2 In the United States, the Toxicodendron genus causes ACD in more than 70% of exposed individuals, leading to medical visits.³ An urgent care visit for a plant-related dermatitis is estimated to cost $168, while an emergency department visit can cost 3 times as much.⁴ Although less common, Compositae plants are another important culprit of plant dermatitis, particularly in gardeners, florists, and farmers. Data from the 2017-2018 North American Contact Dermatitis Group screening series (N=4947) showed sesquiterpene lactones and Compositae to be positive in 0.5% of patch-tested patients.⁵

Plant Dermatitis Classifications

Plant dermatitis can be classified into 5 main categories: ACD, mechanical irritant contact dermatitis, chemical irritant contact dermatitis, light-mediated dermatitis, and pseudophytodermatitis.⁶

Allergic contact dermatitis is an immune-mediated type IV delayed hypersensitivity reaction. The common molecular allergens in plants include phenols, α-methylene-γ-butyrolactones, quinones, terpenes, disulfides, isothiocyanates, and polyacetylenic derivatives.⁶

Plant contact dermatitis due to mechanical and chemical irritants is precipitated by multiple mechanisms, including disruption of the epidermal barrier and subsequent cytokine release from keratinocytes.⁷ Nonimmunologic contact urticaria from plants is thought to be a type of irritant reaction precipitated by mechanical or chemical trauma.⁸

Light-mediated dermatitis includes phytophotodermatitis and photoallergic contact dermatitis. Phytophotodermatitis is a phototoxic reaction triggered by exposure to both plant-derived furanocoumarin and UVA light.⁹ By contrast, photoallergic contact dermatitis is a delayed hypersensitivity reaction from prior sensitization to a light-activated antigen.¹⁰

Pseudophytodermatitis, as its name implies, is not truly mediated by an allergen or irritant intrinsic to the plant but rather by dyes, waxes, insecticides, or arthropods that inhabit the plant or are secondarily applied.⁶

Common Plant Allergens

Anacardiaceae Family
Most of the allergenic plants within the Anacardiaceae family belong to the Toxicodendron genus, which encompasses poison ivy (Toxicodendron radicans), poison oak (Toxicodendron pubescens,Toxicodendron quercifolium, Toxicodendron diversiloum), and poison sumac (Toxicodendron vernix). Poison ivy is the celebrity of the Anacardiaceae family and contributes to most cases of plant-related ACD. It is found in every state in the continental United States. Poison oak is another common culprit found in the western and southeastern United States.¹¹ Plants within the Anacardiaceae family contain an oleoresin called urushiol, which is the primary sensitizing substance. Although poison ivy and poison oak grow well in full sun to partial shade, poison sumac typically is found in damp swampy areas east of the Rocky Mountains. Most cases of ACD related to Anacardiaceae species are due to direct contact with urushiol from a Toxicodendron plant, but burning of brush containing Toxicodendron can cause airborne exposure when urushiol oil is carried by smoke particles.¹² Sensitization to Toxicodendron can cause ACD to other Anacardiaceae species such as the Japanese lacquer tree (Toxicodendron vernicifluum), mango tree (Mangifera indica), cashew tree (Anacardium occidentale), and Indian marking nut tree (Semecarpus anacardium).⁶ Cross-reactions to components of the ginkgo tree (Ginkgo biloba) also are possible.

Toxicodendron plants can be more easily identified and avoided with knowledge of their characteristic leaf patterns. The most dependable way to identify poison ivy and poison oak species is to look for plants with 3 leaves, giving rise to the common saying, “Leaves of three, leave them be.” Poison sumac plants have groups of 7 to 13 leaves arranged as pairs along a central rib. Another helpful finding is a black deposit that Toxicodendron species leave behind following trauma to the leaves. Urushiol oxidizes when exposed to air and turns into a black deposit that can be seen on damaged leaves themselves or can be demonstrated in a black spot test to verify if a plant is a Toxicodendron species. The test is performed by gathering (carefully, without direct contact) a few leaves in a paper towel and crushing them to release sap. Within minutes, the sap will turn black if the plant is indeed a Toxicodendron species.¹³Pruritic, edematous, erythematous papules, plaques, and eventual vesicles in a linear distribution are suspicious for Toxicodendron exposure. Although your pet will not develop Toxicodendron ACD, oleoresin-contaminated pets can transfer the oils to their owners after coming into contact with these plants. Toxicodendron dermatitis also can be acquired from oleoresin-contaminated fomites such as clothing and shoes worn in the garden or when hiking. Toxicodendron dermatitis can appear at different sites on the body at different times depending on the amount of oleoresin exposure as well as epidermal thickness. For example, the oleoresin can be transferred from the hands to body areas with a thinner stratum corneum (eg, genitalia) and cause subsequent dermatitis.¹

Compositae Family
The Compositae family (also known as Asteraceae) is a large plant family with more than 20,000 species, including numerous weeds, wildflowers, and vegetables. The flowers, leaves, stems, and pollens of the Compositae family are coated by cyclic esters called sesquiterpene lactones. Mitchell and Dupuis¹⁴ showed that sesquiterpene lactones are the allergens responsible for ACD to various Compositae plants, including ragweed (Ambrosia), sneezeweed (Helenium), and chrysanthemums (Chrysanthemum). Common Compositae vegetables such as lettuce (Lactuca sativa) have been reported to cause ACD in chefs, grocery store produce handlers, gardeners, and even owners of lettuce-eating pet guinea pigs and turtles.¹⁵ Similarly, artichokes (Cynara scolymus) can cause ACD in gardeners.¹⁶ Exposure to Compositae species also has been implicated in photoallergic reactions, and studies have demonstrated that some patients with chronic actinic dermatitis also have positive patch test reactions to Compositae species and/or sesquiterpene lactones.^17,18

In addition to direct contact with Compositae plants, airborne exposure to sesquiterpene lactones can cause ACD.¹⁴ The pattern of airborne contact dermatitis typically involves exposed areas such as the eyelids, central face, and/or neck. The beak sign also can be a clue to airborne contact dermatitis, which involves dermatitis of the face that spares the nasal tip and/or nasal ridge. It is thought that the beak sign may result from increased sebaceous gland concentration on the nose, which prevents penetration of allergens and irritants.¹⁹ Unlike photoallergic contact dermatitis, which also can involve the face, airborne ACD frequently involves photoprotected areas such as the submandibular chin and the upper lip. Davies and Kersey²⁰ reported the case of a groundsman who was cutting grass with dandelions (Taraxacum officinale) and was found to have associated airborne ACD of the face, neck, and forearms due to Compositae allergy. In a different setting, the aromas of chamomile (Matricaria chamomilla) have been reported to cause airborne ACD in a tea drinker.²¹ Paulsen²² found that ingestion of chamomile tea can induce systemic ACD in sensitized individuals.

Alstroemeriaceae, Liliaceae, and Primulaceae
Florists are exposed to many plant species and have a high prevalence of ACD. Thiboutot et al²³ found that 15 of 57 (26%) floral workers experienced hand dermatitis that cleared with time away from work. The Peruvian lily (Alstroemeria, Alstroemeriaceae family), which contains tuliposide A, was found to be the leading cause of sensitization.²³ Tulips (Tulipa, Liliaceae family), as the flower name suggests, also contain tuliposide A, which along with mechanical irritation from the course tecta fibers on the bulbs lead to a dermatitis known as tulip fingers.^24,25 Poison primrose (Primula obconica, Primulaceae family), cultivated for its highly colorful flowers, contains the contact allergen primin.⁶ A common clinical presentation of ACD for any of these culprit flowers is localized dermatitis of the thumb and index finger in a florist or gardener.

Plants That Cause Irritant Reactions

Cactuses
Although the long spines of the Cactaceae family of cactuses is a warning for passersby, it is the small and nearly invisible barbed hairs (glochids) that inflict a more dramatic cutaneous reaction. The prickly pear cactus (Opuntia species) is a good example of such a plant, as its glochids cause mechanical irritation but also can become embedded in the skin and result in subcutaneous granulomas known as sabra dermatitis.²⁶

Stinging Nettle
The dermatologic term urticaria owes its namesake to the stinging nettle plant, which comes from the family Urticaceae. The stinging nettle has small hairs on its leaves, referred to as stinging trichomes, which have needlelike tips that pierce the skin and inject a mix of histamine, formic acid, and acetylcholine, causing a pruritic dermatitis that may last up to 12 hours.²⁷ The plant is found worldwide and is a common weed in North America.

Phytophotodermatitis

Lemons and limes (Rutaceae family) are common culprits of phytophotodermatitis, often causing what is known as a margarita burn after outdoor consumption or preparation of this tasty citrus beverage.²⁸ An accidental spray of lime juice on the skin while adding it to a beer, guacamole, salsa, or any other food or beverage also can cause phytophotodermatitis.^29-31 Although the juice of lemons and limes contains psoralens, the rind can contain a 6- to 186-fold increased concentration.³² Psoralen is the photoactive agent in Rutaceae plants that intercalates in double-stranded DNA and promotes intrastrand cross-links when exposed to UVA light, which ultimately leads to dermatitis.⁹ Phytophotodermatitis commonly causes erythema, edema, and painful bullae on sun-exposed areas and classically heals with hyperpigmentation.

Pseudophytodermatitis can occur in grain farmers and harvesters who handle wheat and/or barley and incidentally come in contact with insects and chemicals on the plant material. Pseudophytodermatitis from mites in the wheat and/or barley plant can occur at harvest time when contact with the plant material is high. Insects such as the North American itch mite (Pediculoides ventricosus) can cause petechiae, wheals, and pustules. In addition, insecticides such as malathion and arsenical sprays that are applied to plant leaves can cause pseudophytodermatitis, which may be initially diagnosed as dermatitis to the plant itself.⁶

Patch Testing to Plants

When a patient presents with recurrent or persistent dermatitis and a plant contact allergen is suspected, patch testing is indicated. Most comprehensive patch test series contain various plant allergens, such as sesquiterpene lactones, Compositae mix, and limonene hydroperoxides, and patch testing to a specialized plant series may be necessary. Poison ivy/oak/sumac allergens typically are not included in patch test series because of the high prevalence of allergic reactions to these chemicals and the likelihood of sensitization when patch testing with urushiol. Compositae contact sensitization can be difficult to diagnose because neither sesquiterpene lactone mix 0.1% nor parthenolide 0.1% are sensitive enough to pick up all Compositae allergies.^33,34 Paulsen and Andersen³⁴ proposed that if Compositae sensitization is suspected, testing should include sesquiterpene lactone, parthenolide, and Compositae mix II 2.5%, as well as other potential Compositae allergens based on the patient’s history.³⁴

Because plants can have geographic variability and contain potentially unknown allergens,³⁵ testing to plant components may increase the diagnostic yield of patch testing. Dividing the plant into component parts (ie, stem, bulb, leaf, flower) is helpful, as different components have different allergen concentrations. It is important to consult expert resources before proceeding with plant component patch testing because irritant reactions are frequent and may confound the testing.³⁶

Prevention and Treatment

For all plant dermatoses, the mainstay of prevention is to avoid contact with the offending plant material. Gloves can be an important protective tool for plant dermatitis prevention; the correct material depends on the plant species being handled. Rubber gloves should not be worn to protect against Toxicodendron plants since the catechols in urushiol are soluble in rubber; vinyl gloves should be worn instead.⁶ Marks³⁷ found that tuliposide A, the allergen in the Peruvian lily (Alstroemeria), penetrates both vinyl and latex gloves; it does not penetrate nitrile gloves. If exposed, the risk of dermatitis can be decreased if the allergen is washed away with soap and water as soon as possible. Some allergens such as Toxicodendron are absorbed quickly and need to be washed off within 10 minutes of exposure.⁶ Importantly, exposed gardening gloves may continue to perpetuate ACD if the allergen is not also washed off the gloves themselves.

For light-mediated dermatoses, sun avoidance or use of an effective sunscreen can reduce symptoms in an individual who has already been exposed.¹⁰ UVA light activates psoralen-mediated dermatitis but not until 30 to 120 minutes after absorption into the skin.³⁸

Barrier creams are thought to be protective against plant ACD through a variety of mechanisms. The cream itself is meant to reduce skin contact to an allergen or irritant. Additionally, barrier creams contain active ingredients such as silicone, hydrocarbons, and aluminum chlorohydrate, which are thought to trap or transform offending agents before contacting the skin. When contact with a Toxicodendron species is anticipated, Marks et al³⁹ found that dermatitis was absent or significantly reduced when 144 patients were pretreated with quaternium-18 bentonite lotion 5% (P<.0001).

Although allergen avoidance and use of gloves and barrier creams are the mainstays of preventing plant dermatoses, treatment often is required to control postexposure symptoms. For all plant dermatoses, topical corticosteroids can be used to reduce inflammation and pruritus. In some cases, systemic steroids may be necessary. To prevent rebound of dermatitis, patients often require a 3-week or longer course of oral steroids to quell the reaction, particularly if the dermatitis is vigorous or an id reaction is present.⁴⁰ Antihistamines and cold compresses also can provide symptomatic relief.

Final Interpretation

Plants can cause a variety of dermatoses. Although Toxicodendron plants are the most frequent cause of ACD, it is important to keep in mind that florists, gardeners, and farmers are exposed to a large variety of allergens, irritants, and phototoxic agents that cause dermatoses as well. Confirmation of plant-induced ACD involves patch testing against suspected species. Prevention involves use of appropriate barriers and avoidance of implicated plants. Treatment includes topical steroids, antihistamines, and prednisone.

Sea cucumbers—commonly known as trepang in Indonesia, namako in Japan, and hai shen in China, where they are treasured as a food delicacy—are sea creatures belonging to the phylum Echinodermata, class Holothuridea, and family Cucumariidae . ^1,2 They are an integral part of a variety of marine habitats, serving as cleaners as they filter through sediment for nutrients. They can be found on the ocean floor under hundreds of feet of water or in shallow sandy waters along the coast, but they most commonly are found living among coral reefs. Sea cucumbers look just as they sound—shaped like cucumbers or sausages, ranging from under 1 inch to upwards of 6 feet in length depending on the specific species (Figure 1). They have a group of tentacles around the mouth used for filtering sediment, and they move about the ocean floor on tubular feet protruding through the body wall, similar to a sea star.

Beneficial Properties and Cultural Relevance

Although more than 1200 species of sea cucumbers have been identified thus far, only about 20 of these are edible.² The most common of the edible species is Stichopus japonicus, which can be found off the coasts of Korea, China, Japan, and Russia. This particular species most commonly is used in traditional dishes and is divided into 3 groups based on the color: red, green, or black. The price and taste of sea cucumbers varies based on the color, with red being the most expensive.² The body wall of the sea cucumber is cleaned, repeatedly boiled, and dried until edible. It is considered a delicacy, not only in food but also in pharmaceutical forms, as it is comprised of a variety of vitamins, minerals, and other nutrients that are thought to provide anticancer, anticoagulant, antioxidant, antifungal, and anti-inflammatory properties. Components of the body wall include collagen, mucopolysaccharides, peptides, gelatin, glycosaminoglycans, glycosides (including various holotoxins), hydroxylates, saponins, and fatty acids.² The regenerative properties of the sea cucumber also are important in future biomedical developments.

Toxic Properties

Although sea cucumbers have proven to have many beneficial properties, at least 30 species also produce potent toxins that pose a danger to both humans and other wildlife.³ The toxins are collectively referred to as holothurin; however, specific species actually produce a variety of holothurin toxins with unique chemical structures. Each toxin is a variation of a specific triterpene glycoside called saponins, which are common glycosides in the plant world. Holothurin was the first saponin to be found in animals. The only animals known to contain holothurin are the echinoderms, including sea cucumbers and sea stars.¹ Holothurins A and B are the 2 groups of holothurin toxins produced specifically by sea cucumbers. The toxins are composed of roughly 60% glycosides and pigment; 30% free amino acids (alanine, arginine, cysteine, glycine, glutamic acid, histidine, serine, and valine); 5% to 10% insoluble proteins; and 1% cholesterol, salts, and polypeptides.³

Holothurins are concentrated in granules within specialized structures of the sea cucumber called Cuvierian tubules, which freely float in the posterior coelomic cavity of the sea cucumber and are attached at the base of the respiratory tree. It is with these tubules that sea cucumbers utilize a unique defensive mechanism. Upon disturbance, the sea cucumber will turn its posterior end to the threat and squeeze its body in a series of violent contractions, inducing a tear in the cloacal wall.⁴ The tubules pass through this tear, are autotomized from the attachment point at the respiratory tree, and are finally expelled through the anus onto the predator and into the surrounding waters. The tubules are both sticky on contact and poisonous due to the holothurin, allowing the sea cucumber to crawl away from the threat unscathed. Over time, the tubules will regenerate, allowing the sea cucumber to protect itself again in the face of future danger.

Aside from direct disturbance by a threat, sea cucumbers also are known to undergo evisceration due to high temperatures and oxygen deficiency.³ Species that lack Cuvierian tubules can still produce holothurin toxins, though the toxins are secreted onto the outer surface of the body wall and mainly pose a risk with direct contact undiluted by seawater.⁵ The toxin induces a neural blockade in other sea creatures through its interaction with ion channels. On Asian islands, sea cucumbers have been exploited for this ability and commonly are thrown into tidal pools by fishermen to paralyze fish for easier capture.¹

Effects on Human Skin

In humans, the holothurin toxins of sea cucumbers cause an acute irritant dermatitis upon contact with the skin.⁶ Fishermen or divers handling sea cucumbers without gloves may present with an irritant contact dermatitis characterized by marked erythema and swelling (Figure 2).^6-8 Additionally, holothurin toxins can cause irritation of the mucous membranes of the eyes and mouth. Contact with the mucous membranes of the eyes can induce a painful conjunctivitis that may result in blindness.^6,8 Ingestion of large quantities of sea cucumber can produce an anticoagulant effect, and toxins in some species act similar to cardiac glycosides.^3,9

In addition to their own toxins, sea cucumbers also can secrete undigested nematocysts of previously consumed cnidarians through the integument.^7,10 In this case, the result of direct contact with the body wall is similar to a jellyfish sting in addition to the irritant contact dermatitis caused by the holothurin toxin.

Treatment and Prevention

Irritant dermatitis resulting from contact with a holothurin toxin is first treated with cleansing of the affected area at the time of exposure with generous amounts of seawater or preferably hot seawater and soap. Most marine toxins are inactivated by heat, but holothurin is partially heat stable. Vinegar or isopropyl alcohol also have been used.⁹ The result is removal of the slime containing the holothurin toxin rather than deactivation of the toxin. Although this alone may relieve symptoms, dermatitis also may be addressed with topical anesthetics, corticosteroids, or, if a severe reaction has occurred, systemic steroids.⁹

Conjunctivitis should be addressed with copious irrigation with tap water and topical anesthesia. Following proper irrigation, providers may choose to follow up with fluorescein staining to rule out corneal injury.¹⁰

The dermatologic effects of holothurin toxins can be prevented with the use of gloves and diving masks or goggles. Proper protective wear should be utilized not only when directly handling sea cucumbers but also when swimming in water where sea cucumbers may be present. Systemic toxicity can be prevented by proper cooking, as holothurin toxins are only partially heat resistant and also are hydrolyzed into nontoxic products by gastric acid. Additionally, the species of the sea cucumber should be confirmed prior to consumption, as edible species are known to contain less toxin.¹

Conclusion

Although sea cucumbers have ecologic, culinary, and pharmaceutical value, they also can pose a threat to both humans and wildlife. The holothurin toxins produced by sea cucumbers cause a painful contact dermatitis and can lead to conjunctivitis and even blindness following eye exposure. Although the toxin is broken down into nontoxic metabolites by gastric acid, large amounts of potent variants can induce systemic effects. Individuals who come in contact with sea cucumbers, such as fishermen and divers, should utilize proper protection including gloves and protective eyewear.

Sea cucumbers—commonly known as trepang in Indonesia, namako in Japan, and hai shen in China, where they are treasured as a food delicacy—are sea creatures belonging to the phylum Echinodermata, class Holothuridea, and family Cucumariidae . ^1,2 They are an integral part of a variety of marine habitats, serving as cleaners as they filter through sediment for nutrients. They can be found on the ocean floor under hundreds of feet of water or in shallow sandy waters along the coast, but they most commonly are found living among coral reefs. Sea cucumbers look just as they sound—shaped like cucumbers or sausages, ranging from under 1 inch to upwards of 6 feet in length depending on the specific species (Figure 1). They have a group of tentacles around the mouth used for filtering sediment, and they move about the ocean floor on tubular feet protruding through the body wall, similar to a sea star.

Beneficial Properties and Cultural Relevance

Although more than 1200 species of sea cucumbers have been identified thus far, only about 20 of these are edible.² The most common of the edible species is Stichopus japonicus, which can be found off the coasts of Korea, China, Japan, and Russia. This particular species most commonly is used in traditional dishes and is divided into 3 groups based on the color: red, green, or black. The price and taste of sea cucumbers varies based on the color, with red being the most expensive.² The body wall of the sea cucumber is cleaned, repeatedly boiled, and dried until edible. It is considered a delicacy, not only in food but also in pharmaceutical forms, as it is comprised of a variety of vitamins, minerals, and other nutrients that are thought to provide anticancer, anticoagulant, antioxidant, antifungal, and anti-inflammatory properties. Components of the body wall include collagen, mucopolysaccharides, peptides, gelatin, glycosaminoglycans, glycosides (including various holotoxins), hydroxylates, saponins, and fatty acids.² The regenerative properties of the sea cucumber also are important in future biomedical developments.

Toxic Properties

Although sea cucumbers have proven to have many beneficial properties, at least 30 species also produce potent toxins that pose a danger to both humans and other wildlife.³ The toxins are collectively referred to as holothurin; however, specific species actually produce a variety of holothurin toxins with unique chemical structures. Each toxin is a variation of a specific triterpene glycoside called saponins, which are common glycosides in the plant world. Holothurin was the first saponin to be found in animals. The only animals known to contain holothurin are the echinoderms, including sea cucumbers and sea stars.¹ Holothurins A and B are the 2 groups of holothurin toxins produced specifically by sea cucumbers. The toxins are composed of roughly 60% glycosides and pigment; 30% free amino acids (alanine, arginine, cysteine, glycine, glutamic acid, histidine, serine, and valine); 5% to 10% insoluble proteins; and 1% cholesterol, salts, and polypeptides.³

Holothurins are concentrated in granules within specialized structures of the sea cucumber called Cuvierian tubules, which freely float in the posterior coelomic cavity of the sea cucumber and are attached at the base of the respiratory tree. It is with these tubules that sea cucumbers utilize a unique defensive mechanism. Upon disturbance, the sea cucumber will turn its posterior end to the threat and squeeze its body in a series of violent contractions, inducing a tear in the cloacal wall.⁴ The tubules pass through this tear, are autotomized from the attachment point at the respiratory tree, and are finally expelled through the anus onto the predator and into the surrounding waters. The tubules are both sticky on contact and poisonous due to the holothurin, allowing the sea cucumber to crawl away from the threat unscathed. Over time, the tubules will regenerate, allowing the sea cucumber to protect itself again in the face of future danger.

Aside from direct disturbance by a threat, sea cucumbers also are known to undergo evisceration due to high temperatures and oxygen deficiency.³ Species that lack Cuvierian tubules can still produce holothurin toxins, though the toxins are secreted onto the outer surface of the body wall and mainly pose a risk with direct contact undiluted by seawater.⁵ The toxin induces a neural blockade in other sea creatures through its interaction with ion channels. On Asian islands, sea cucumbers have been exploited for this ability and commonly are thrown into tidal pools by fishermen to paralyze fish for easier capture.¹

Effects on Human Skin

In humans, the holothurin toxins of sea cucumbers cause an acute irritant dermatitis upon contact with the skin.⁶ Fishermen or divers handling sea cucumbers without gloves may present with an irritant contact dermatitis characterized by marked erythema and swelling (Figure 2).^6-8 Additionally, holothurin toxins can cause irritation of the mucous membranes of the eyes and mouth. Contact with the mucous membranes of the eyes can induce a painful conjunctivitis that may result in blindness.^6,8 Ingestion of large quantities of sea cucumber can produce an anticoagulant effect, and toxins in some species act similar to cardiac glycosides.^3,9

In addition to their own toxins, sea cucumbers also can secrete undigested nematocysts of previously consumed cnidarians through the integument.^7,10 In this case, the result of direct contact with the body wall is similar to a jellyfish sting in addition to the irritant contact dermatitis caused by the holothurin toxin.

Treatment and Prevention

Irritant dermatitis resulting from contact with a holothurin toxin is first treated with cleansing of the affected area at the time of exposure with generous amounts of seawater or preferably hot seawater and soap. Most marine toxins are inactivated by heat, but holothurin is partially heat stable. Vinegar or isopropyl alcohol also have been used.⁹ The result is removal of the slime containing the holothurin toxin rather than deactivation of the toxin. Although this alone may relieve symptoms, dermatitis also may be addressed with topical anesthetics, corticosteroids, or, if a severe reaction has occurred, systemic steroids.⁹

Conjunctivitis should be addressed with copious irrigation with tap water and topical anesthesia. Following proper irrigation, providers may choose to follow up with fluorescein staining to rule out corneal injury.¹⁰

The dermatologic effects of holothurin toxins can be prevented with the use of gloves and diving masks or goggles. Proper protective wear should be utilized not only when directly handling sea cucumbers but also when swimming in water where sea cucumbers may be present. Systemic toxicity can be prevented by proper cooking, as holothurin toxins are only partially heat resistant and also are hydrolyzed into nontoxic products by gastric acid. Additionally, the species of the sea cucumber should be confirmed prior to consumption, as edible species are known to contain less toxin.¹

Conclusion

Although sea cucumbers have ecologic, culinary, and pharmaceutical value, they also can pose a threat to both humans and wildlife. The holothurin toxins produced by sea cucumbers cause a painful contact dermatitis and can lead to conjunctivitis and even blindness following eye exposure. Although the toxin is broken down into nontoxic metabolites by gastric acid, large amounts of potent variants can induce systemic effects. Individuals who come in contact with sea cucumbers, such as fishermen and divers, should utilize proper protection including gloves and protective eyewear.

Sea cucumbers—commonly known as trepang in Indonesia, namako in Japan, and hai shen in China, where they are treasured as a food delicacy—are sea creatures belonging to the phylum Echinodermata, class Holothuridea, and family Cucumariidae . ^1,2 They are an integral part of a variety of marine habitats, serving as cleaners as they filter through sediment for nutrients. They can be found on the ocean floor under hundreds of feet of water or in shallow sandy waters along the coast, but they most commonly are found living among coral reefs. Sea cucumbers look just as they sound—shaped like cucumbers or sausages, ranging from under 1 inch to upwards of 6 feet in length depending on the specific species (Figure 1). They have a group of tentacles around the mouth used for filtering sediment, and they move about the ocean floor on tubular feet protruding through the body wall, similar to a sea star.

Beneficial Properties and Cultural Relevance

Although more than 1200 species of sea cucumbers have been identified thus far, only about 20 of these are edible.² The most common of the edible species is Stichopus japonicus, which can be found off the coasts of Korea, China, Japan, and Russia. This particular species most commonly is used in traditional dishes and is divided into 3 groups based on the color: red, green, or black. The price and taste of sea cucumbers varies based on the color, with red being the most expensive.² The body wall of the sea cucumber is cleaned, repeatedly boiled, and dried until edible. It is considered a delicacy, not only in food but also in pharmaceutical forms, as it is comprised of a variety of vitamins, minerals, and other nutrients that are thought to provide anticancer, anticoagulant, antioxidant, antifungal, and anti-inflammatory properties. Components of the body wall include collagen, mucopolysaccharides, peptides, gelatin, glycosaminoglycans, glycosides (including various holotoxins), hydroxylates, saponins, and fatty acids.² The regenerative properties of the sea cucumber also are important in future biomedical developments.

Toxic Properties

Although sea cucumbers have proven to have many beneficial properties, at least 30 species also produce potent toxins that pose a danger to both humans and other wildlife.³ The toxins are collectively referred to as holothurin; however, specific species actually produce a variety of holothurin toxins with unique chemical structures. Each toxin is a variation of a specific triterpene glycoside called saponins, which are common glycosides in the plant world. Holothurin was the first saponin to be found in animals. The only animals known to contain holothurin are the echinoderms, including sea cucumbers and sea stars.¹ Holothurins A and B are the 2 groups of holothurin toxins produced specifically by sea cucumbers. The toxins are composed of roughly 60% glycosides and pigment; 30% free amino acids (alanine, arginine, cysteine, glycine, glutamic acid, histidine, serine, and valine); 5% to 10% insoluble proteins; and 1% cholesterol, salts, and polypeptides.³

Holothurins are concentrated in granules within specialized structures of the sea cucumber called Cuvierian tubules, which freely float in the posterior coelomic cavity of the sea cucumber and are attached at the base of the respiratory tree. It is with these tubules that sea cucumbers utilize a unique defensive mechanism. Upon disturbance, the sea cucumber will turn its posterior end to the threat and squeeze its body in a series of violent contractions, inducing a tear in the cloacal wall.⁴ The tubules pass through this tear, are autotomized from the attachment point at the respiratory tree, and are finally expelled through the anus onto the predator and into the surrounding waters. The tubules are both sticky on contact and poisonous due to the holothurin, allowing the sea cucumber to crawl away from the threat unscathed. Over time, the tubules will regenerate, allowing the sea cucumber to protect itself again in the face of future danger.

Aside from direct disturbance by a threat, sea cucumbers also are known to undergo evisceration due to high temperatures and oxygen deficiency.³ Species that lack Cuvierian tubules can still produce holothurin toxins, though the toxins are secreted onto the outer surface of the body wall and mainly pose a risk with direct contact undiluted by seawater.⁵ The toxin induces a neural blockade in other sea creatures through its interaction with ion channels. On Asian islands, sea cucumbers have been exploited for this ability and commonly are thrown into tidal pools by fishermen to paralyze fish for easier capture.¹

Effects on Human Skin

In humans, the holothurin toxins of sea cucumbers cause an acute irritant dermatitis upon contact with the skin.⁶ Fishermen or divers handling sea cucumbers without gloves may present with an irritant contact dermatitis characterized by marked erythema and swelling (Figure 2).^6-8 Additionally, holothurin toxins can cause irritation of the mucous membranes of the eyes and mouth. Contact with the mucous membranes of the eyes can induce a painful conjunctivitis that may result in blindness.^6,8 Ingestion of large quantities of sea cucumber can produce an anticoagulant effect, and toxins in some species act similar to cardiac glycosides.^3,9

In addition to their own toxins, sea cucumbers also can secrete undigested nematocysts of previously consumed cnidarians through the integument.^7,10 In this case, the result of direct contact with the body wall is similar to a jellyfish sting in addition to the irritant contact dermatitis caused by the holothurin toxin.

Treatment and Prevention

Irritant dermatitis resulting from contact with a holothurin toxin is first treated with cleansing of the affected area at the time of exposure with generous amounts of seawater or preferably hot seawater and soap. Most marine toxins are inactivated by heat, but holothurin is partially heat stable. Vinegar or isopropyl alcohol also have been used.⁹ The result is removal of the slime containing the holothurin toxin rather than deactivation of the toxin. Although this alone may relieve symptoms, dermatitis also may be addressed with topical anesthetics, corticosteroids, or, if a severe reaction has occurred, systemic steroids.⁹

Conjunctivitis should be addressed with copious irrigation with tap water and topical anesthesia. Following proper irrigation, providers may choose to follow up with fluorescein staining to rule out corneal injury.¹⁰

The dermatologic effects of holothurin toxins can be prevented with the use of gloves and diving masks or goggles. Proper protective wear should be utilized not only when directly handling sea cucumbers but also when swimming in water where sea cucumbers may be present. Systemic toxicity can be prevented by proper cooking, as holothurin toxins are only partially heat resistant and also are hydrolyzed into nontoxic products by gastric acid. Additionally, the species of the sea cucumber should be confirmed prior to consumption, as edible species are known to contain less toxin.¹

Conclusion

Although sea cucumbers have ecologic, culinary, and pharmaceutical value, they also can pose a threat to both humans and wildlife. The holothurin toxins produced by sea cucumbers cause a painful contact dermatitis and can lead to conjunctivitis and even blindness following eye exposure. Although the toxin is broken down into nontoxic metabolites by gastric acid, large amounts of potent variants can induce systemic effects. Individuals who come in contact with sea cucumbers, such as fishermen and divers, should utilize proper protection including gloves and protective eyewear.

Irritable bowel syndrome (IBS) is one of the most common disorders managed by primary care physicians and gastroenterologists.¹ Characterized by abdominal pain coinciding with altered stool form and/or frequency as defined by the Rome IV diagnostic criteria,² symptoms range from mild to debilitating and may remarkably impair quality of life and work productivity.¹

The cause of IBS is poorly understood. Proposed pathophysiologic factors include impaired mucosal function, microbial imbalance, visceral hypersensitivity, psychologic dysfunction, genetic factors, neurotransmitter imbalance, postinfectious gastroenteritis, inflammation, and food intolerance, any or all of which may lead to the development and maintenance of IBS symptoms.³ More recent observations of inflammation in the intestinal lining^4,5 and proinflammatory peripherally circulating cytokines⁶ challenge its traditional classification as a functional disorder.

The cause of this inflammation is of intense interest, with speculation that the bacterial microbiota, bile acids, association with postinfectious gastroenteritis and inflammatory bowel disease cases, and/or foods may contribute. Although approximately 50% of individuals with IBS report that foods aggravate their symptoms,⁷ studies investigating type I antibody–mediated immediate hypersensitivity have largely failed to demonstrate a substantial link, prompting many authorities to regard these associations as food “intolerances” rather than true allergies. Based on this body of literature, a large 2010 consensus report on all aspects of food allergies advises against food allergy testing for IBS.⁸

In contrast, by utilizing type IV food allergen skin patch testing, 2 proof-of-concept studies^9,10 investigated a different allergic mechanism in IBS, namely cell-mediated delayed-type hypersensitivity. Because many foods and food additives are known to cause allergic contact dermatitis,¹¹ it was hypothesized that these foods may elicit a similar delayed-type hypersensitivity response in the intestinal lining in previously sensitized individuals. By following a patch test–guided food avoidance diet, a large subpopulation of patients with IBS experienced partial or complete IBS symptom relief.^9,10 Our study further investigates a role for food-related delayed-type hypersensitivities in the pathogenesis of IBS.

Methods

Patient Selection
This study was conducted in a secondary care community-based setting. All patients were self-referred over an 18-month period ending in October 2019, had physician-diagnosed IBS, and/or met the Rome IV criteria for IBS and presented expressly for the food patch testing on a fee-for-service basis. Subtype of IBS was determined on presentation by the self-reported historically predominant symptom. Duration of IBS symptoms was self-reported and was rounded to the nearest year for purposes of data collection.

Exclusion criteria included pregnancy, known allergy to adhesive tape or any of the food allergens used in the study, severe skin rash, symptoms that had a known cause other than IBS, or active treatment with systemic immunosuppressive medications.

Patch Testing
Skin patch testing was initiated using an extensive panel of 117 type IV food allergens (eTable)¹¹ identified in the literature,¹² most of which utilized standard compounded formulations¹³ or were available from reputable patch test manufacturers (Brial Allergen GmbH; Chemotechnique Diagnostics). This panel was not approved by the US Food and Drug Administration. The freeze-dried vegetable formulations were taken from the 2018 report.⁹ Standard skin patch test procedure protocols¹² were used, affixing the patches to the upper aspect of the back.

Following patch test application on day 1, two follow-up visits occurred on day 3 and either day 4 or day 5. On day 3, patches were removed, and the initial results were read by a board-certified dermatologist according to a standard grading system.¹⁴ Interpretation of patch tests included no reaction, questionable reaction consisting of macular erythema, weak reaction consisting of erythema and slight edema, or strong reaction consisting of erythema and marked edema. On day 4 or day 5, the final patch test reading was performed, and patients were informed of their results. Patients were advised to avoid ingestion of all foods that elicited a questionable or positive patch test response for at least 3 months, and information about the foods and their avoidance also was distributed and reviewed.

Food Avoidance Questionnaire
Patients with questionable or positive patch tests at 72 or 96 hours were advised of their eligibility to participate in an institutional review board–approved food avoidance questionnaire study investigating the utility of patch test–guided food avoidance on IBS symptoms. The questionnaire assessed the following: (1) baseline average abdominal pain prior to patch test–guided avoidance diet (0=no symptoms; 10=very severe); (2) average abdominal pain since initiation of patch test–guided avoidance diet (0=no symptoms; 10=very severe); (3) degree of improvement in overall IBS symptoms by the end of the food avoidance period (0=no improvement; 10=great improvement); (4) compliance with the avoidance diet for the duration of the avoidance period (completely, partially, not at all, or not sure).

Questionnaires and informed consent were mailed to patients via the US Postal Service 3 months after completing the patch testing. The questionnaire and consent were to be completed and returned after dietary avoidance of the identified allergens for at least 3 months. Patients were not compensated for participation in the study.

Statistical Analysis
Statistical analysis of data collected from study questionnaires was performed with Microsoft Excel. Mean abdominal pain and mean global improvement scores were reported along with 1 SD of the mean. For comparison of mean abdominal pain and improvement in global IBS symptoms from baseline to after 3 months of identified allergen avoidance, a Mann-Whitney U test was performed, with P<.05 being considered statistically significant.

Results

Thirty-seven consecutive patients underwent the testing and were eligible for the study. Nineteen patients were included in the study by virtue of completing and returning their posttest food avoidance questionnaire and informed consent. Eighteen patients were White and 1 was Asian. Subcategories of IBS were diarrhea predominant (9 [47.4%]), constipation predominant (3 [15.8%]), mixed type (5 [26.3%]), and undetermined type (2 [10.5%]). Questionnaire answers were reported after a mean (SD) duration of patch test–directed food avoidance of 4.5 (3.0) months (Table 1).

Overall Improvement
Fifteen (78.9%) patients reported at least slight to great improvement in their global IBS symptoms, and 4 (21.1%) reported no improvement (Table 2), with a mean (SD) improvement score of 5.1 (3.3)(P<.00001).

Comment

Despite intense research interest and a growing number of new medications for IBS approved by the US Food and Drug Administration, there remains a large void in the search for cost-effective and efficacious approaches for IBS evaluation and treatment. In addition to major disturbances in quality of life,^14,15 the cost to society in direct medical expenses and indirect costs associated with loss of productivity and work absenteeism is considerable; estimates range from $21 billion or more annually.¹⁶

Food Hypersensitivities Triggering IBS
This study further evaluated a role for skin patch testing to identify delayed-type (type IV) food hypersensitivities that trigger IBS symptoms and differed from the prior investigations^9,10 in that the symptoms used to define IBS were updated from the Rome III¹⁷ to the newer Rome IV² criteria. The data presented here show moderate to great improvement in global IBS symptoms in 58% (11/19) of patients, which is in line with a 2018 report of 40 study participants for whom follow-up at 3 or more months was available,⁹ providing additional support for a role for type IV food allergies in causing the same gastrointestinal tract symptoms that define IBS. The distinction between food-related studies, including this one, that implicate food allergies^9,10 and prior studies that did not support a role for food allergies in IBS pathogenesis⁸ can be accounted for by the type of allergy investigated. Conclusions that IBS flares after food ingestion were attributable to intolerance rather than true allergy were based on results investigating only the humoral arm and failed to consider the cell-mediated arm of the immune system. As such, foods that appear to trigger IBS symptoms on an allergic basis in our study are recognized in the literature¹² as type IV allergens that elicit cell-mediated immunologic responses rather than more widely recognized type I allergens, such as peanuts and shellfish, that elicit immediate-type hypersensitivity responses. Although any type IV food allergen(s) could be responsible, a pattern emerged in this study and the study published in 2018.⁹ Namely, some foods stood out as more frequently inducing patch test reactions, with the 3 most common being carmine, cinnamon bark oil, and sodium bisulfite (eTable). The sample size is relatively small, but the results raise the question of whether these foods are the most likely to trigger IBS symptoms in the general population. If so, is it the result of a higher innate sensitizing potential and/or a higher frequency of exposure in commonly eaten foods? Larger randomized clinical trials are needed.

Immune Response and IBS
There is mounting evidence that the immune system may play a role in the pathophysiology of IBS.¹⁸ Both lymphocyte infiltration of the myenteric plexus and an increase in intestinal mucosal T lymphocytes have been observed, and it is generally accepted that the mucosal immune system seems to be activated, at least in a subset of patients with IBS.¹⁹ Irritable bowel syndrome associations with quiescent inflammatory bowel disease or postinfectious gastroenteritis provide 2 potential causes for the inflammation, but most IBS patients have had neither.²⁰ The mucosal lining of the intestine and immune system have vast exposure to intraluminal allergens in transit, and it is hypothesized that the same delayed-type hypersensitivity response elicited in the skin by patch testing is elicited in the intestine, resulting in the inflammation that triggers IBS symptoms.¹⁰ The results here add to the growing body of evidence that ingestion of type IV food allergens by previously sensitized individuals could, in fact, be the primary source of the inflammation observed in a large subpopulation of individuals who carry a diagnosis of IBS.

Food Allergens in Patch Testing
Many of the food allergens used in this study are commonly found in various nonfood products that may contact the skin. For example, many flavorings are used as fragrances, and many preservatives, binders, thickeners, emulsifiers, and stabilizers serve the same role in moisturizers, cosmetics, and topical medications. Likewise, nickel sulfate hexahydrate, ubiquitous in foods that arise from the earth, often is found in metal in jewelry, clothing components, and cell phones. All are potential sensitizers. Thus, the question may arise whether the causal relationship between the food allergens identified by patch testing and IBS symptoms might be more of a systemic effect akin to systemic contact dermatitis as sometimes follows ingestion of an allergen to which an individual has been topically sensitized, rather than the proposed localized immunologic response in the intestinal lining. We were unaware of patient history of allergic contact dermatitis to any of the patch test allergens in this study, but the dermatologist author here (M.S.) has unpublished experience with 2 other patients with IBS who have benefited from low-nickel diets after having had positive patch tests to nickel sulfate hexahydrate and who, in retrospect, did report a history of earring dermatitis. Future investigations using pre– and post–food challenge histologic assessments of the intestinal mucosa in patients who benefit from patch test–guided food avoidance diets should help to better define the mechanism.

Because IBS has not been traditionally associated with structural or biochemical abnormalities detectable with current routine diagnostic tools, it has long been viewed as a functional disorder. The findings published more recently,^9,10 in addition to this study’s results, would negate this functional classification in the subset of patients with IBS symptoms who experience sustained relief of their symptoms by patch test–directed food avoidance. The underlying delayed-type hypersensitivity pathogenesis of the IBS-like symptoms in these individuals would mandate an organic classification, aptly named allergic contact enteritis.¹⁰

Follow-up Data
The mean (SD) follow-up duration for this study and the 2018 report⁹ was 4.5 (3.0) months and 7.6 (3.9) months, respectively. The placebo effect is a concern for disorders such as IBS in which primarily subjective outcome measures are available,²¹ and in a retrospective analysis of 25 randomized, placebo-controlled IBS clinical trials, Spiller²² concluded the optimum length of such trials to be more than 3 months, which these studies exceed. Although not blinded or placebo controlled, the length of follow-up in the 2018 report⁹ and here enhances the validity of the results.

Limitation
The retrospective manner in which the self-assessments were reported in this study introduces the potential for recall bias, a variable that could affect results. The presence and direction of bias by any given individual cannot be known, making it difficult to determine any effect it may have had. Further investigation should include daily assessments and refine the primary study end points to include both abdominal pain and the defecation considerations that define IBS.

Conclusion

Food patch testing has the potential to offer a safe, cost-effective approach to the evaluation and management of IBS symptoms. Randomized clinical trials are needed to further investigate the validity of the proof-of-concept results to date. For patients who benefit from a patch test–guided avoidance diet, invasive and costly endoscopic, radiologic, and laboratory testing and pharmacologic management could be averted. Symptomatic relief could be attained simply by avoiding the implicated foods, essentially doing more by doing less. 


Irritable bowel syndrome (IBS) is one of the most common disorders managed by primary care physicians and gastroenterologists.¹ Characterized by abdominal pain coinciding with altered stool form and/or frequency as defined by the Rome IV diagnostic criteria,² symptoms range from mild to debilitating and may remarkably impair quality of life and work productivity.¹

The cause of IBS is poorly understood. Proposed pathophysiologic factors include impaired mucosal function, microbial imbalance, visceral hypersensitivity, psychologic dysfunction, genetic factors, neurotransmitter imbalance, postinfectious gastroenteritis, inflammation, and food intolerance, any or all of which may lead to the development and maintenance of IBS symptoms.³ More recent observations of inflammation in the intestinal lining^4,5 and proinflammatory peripherally circulating cytokines⁶ challenge its traditional classification as a functional disorder.

The cause of this inflammation is of intense interest, with speculation that the bacterial microbiota, bile acids, association with postinfectious gastroenteritis and inflammatory bowel disease cases, and/or foods may contribute. Although approximately 50% of individuals with IBS report that foods aggravate their symptoms,⁷ studies investigating type I antibody–mediated immediate hypersensitivity have largely failed to demonstrate a substantial link, prompting many authorities to regard these associations as food “intolerances” rather than true allergies. Based on this body of literature, a large 2010 consensus report on all aspects of food allergies advises against food allergy testing for IBS.⁸

In contrast, by utilizing type IV food allergen skin patch testing, 2 proof-of-concept studies^9,10 investigated a different allergic mechanism in IBS, namely cell-mediated delayed-type hypersensitivity. Because many foods and food additives are known to cause allergic contact dermatitis,¹¹ it was hypothesized that these foods may elicit a similar delayed-type hypersensitivity response in the intestinal lining in previously sensitized individuals. By following a patch test–guided food avoidance diet, a large subpopulation of patients with IBS experienced partial or complete IBS symptom relief.^9,10 Our study further investigates a role for food-related delayed-type hypersensitivities in the pathogenesis of IBS.

Methods

Patient Selection
This study was conducted in a secondary care community-based setting. All patients were self-referred over an 18-month period ending in October 2019, had physician-diagnosed IBS, and/or met the Rome IV criteria for IBS and presented expressly for the food patch testing on a fee-for-service basis. Subtype of IBS was determined on presentation by the self-reported historically predominant symptom. Duration of IBS symptoms was self-reported and was rounded to the nearest year for purposes of data collection.

Exclusion criteria included pregnancy, known allergy to adhesive tape or any of the food allergens used in the study, severe skin rash, symptoms that had a known cause other than IBS, or active treatment with systemic immunosuppressive medications.

Patch Testing
Skin patch testing was initiated using an extensive panel of 117 type IV food allergens (eTable)¹¹ identified in the literature,¹² most of which utilized standard compounded formulations¹³ or were available from reputable patch test manufacturers (Brial Allergen GmbH; Chemotechnique Diagnostics). This panel was not approved by the US Food and Drug Administration. The freeze-dried vegetable formulations were taken from the 2018 report.⁹ Standard skin patch test procedure protocols¹² were used, affixing the patches to the upper aspect of the back.

Following patch test application on day 1, two follow-up visits occurred on day 3 and either day 4 or day 5. On day 3, patches were removed, and the initial results were read by a board-certified dermatologist according to a standard grading system.¹⁴ Interpretation of patch tests included no reaction, questionable reaction consisting of macular erythema, weak reaction consisting of erythema and slight edema, or strong reaction consisting of erythema and marked edema. On day 4 or day 5, the final patch test reading was performed, and patients were informed of their results. Patients were advised to avoid ingestion of all foods that elicited a questionable or positive patch test response for at least 3 months, and information about the foods and their avoidance also was distributed and reviewed.

Food Avoidance Questionnaire
Patients with questionable or positive patch tests at 72 or 96 hours were advised of their eligibility to participate in an institutional review board–approved food avoidance questionnaire study investigating the utility of patch test–guided food avoidance on IBS symptoms. The questionnaire assessed the following: (1) baseline average abdominal pain prior to patch test–guided avoidance diet (0=no symptoms; 10=very severe); (2) average abdominal pain since initiation of patch test–guided avoidance diet (0=no symptoms; 10=very severe); (3) degree of improvement in overall IBS symptoms by the end of the food avoidance period (0=no improvement; 10=great improvement); (4) compliance with the avoidance diet for the duration of the avoidance period (completely, partially, not at all, or not sure).

Questionnaires and informed consent were mailed to patients via the US Postal Service 3 months after completing the patch testing. The questionnaire and consent were to be completed and returned after dietary avoidance of the identified allergens for at least 3 months. Patients were not compensated for participation in the study.

Statistical Analysis
Statistical analysis of data collected from study questionnaires was performed with Microsoft Excel. Mean abdominal pain and mean global improvement scores were reported along with 1 SD of the mean. For comparison of mean abdominal pain and improvement in global IBS symptoms from baseline to after 3 months of identified allergen avoidance, a Mann-Whitney U test was performed, with P<.05 being considered statistically significant.

Results

Thirty-seven consecutive patients underwent the testing and were eligible for the study. Nineteen patients were included in the study by virtue of completing and returning their posttest food avoidance questionnaire and informed consent. Eighteen patients were White and 1 was Asian. Subcategories of IBS were diarrhea predominant (9 [47.4%]), constipation predominant (3 [15.8%]), mixed type (5 [26.3%]), and undetermined type (2 [10.5%]). Questionnaire answers were reported after a mean (SD) duration of patch test–directed food avoidance of 4.5 (3.0) months (Table 1).

Overall Improvement
Fifteen (78.9%) patients reported at least slight to great improvement in their global IBS symptoms, and 4 (21.1%) reported no improvement (Table 2), with a mean (SD) improvement score of 5.1 (3.3)(P<.00001).

Comment

Despite intense research interest and a growing number of new medications for IBS approved by the US Food and Drug Administration, there remains a large void in the search for cost-effective and efficacious approaches for IBS evaluation and treatment. In addition to major disturbances in quality of life,^14,15 the cost to society in direct medical expenses and indirect costs associated with loss of productivity and work absenteeism is considerable; estimates range from $21 billion or more annually.¹⁶

Food Hypersensitivities Triggering IBS
This study further evaluated a role for skin patch testing to identify delayed-type (type IV) food hypersensitivities that trigger IBS symptoms and differed from the prior investigations^9,10 in that the symptoms used to define IBS were updated from the Rome III¹⁷ to the newer Rome IV² criteria. The data presented here show moderate to great improvement in global IBS symptoms in 58% (11/19) of patients, which is in line with a 2018 report of 40 study participants for whom follow-up at 3 or more months was available,⁹ providing additional support for a role for type IV food allergies in causing the same gastrointestinal tract symptoms that define IBS. The distinction between food-related studies, including this one, that implicate food allergies^9,10 and prior studies that did not support a role for food allergies in IBS pathogenesis⁸ can be accounted for by the type of allergy investigated. Conclusions that IBS flares after food ingestion were attributable to intolerance rather than true allergy were based on results investigating only the humoral arm and failed to consider the cell-mediated arm of the immune system. As such, foods that appear to trigger IBS symptoms on an allergic basis in our study are recognized in the literature¹² as type IV allergens that elicit cell-mediated immunologic responses rather than more widely recognized type I allergens, such as peanuts and shellfish, that elicit immediate-type hypersensitivity responses. Although any type IV food allergen(s) could be responsible, a pattern emerged in this study and the study published in 2018.⁹ Namely, some foods stood out as more frequently inducing patch test reactions, with the 3 most common being carmine, cinnamon bark oil, and sodium bisulfite (eTable). The sample size is relatively small, but the results raise the question of whether these foods are the most likely to trigger IBS symptoms in the general population. If so, is it the result of a higher innate sensitizing potential and/or a higher frequency of exposure in commonly eaten foods? Larger randomized clinical trials are needed.

Immune Response and IBS
There is mounting evidence that the immune system may play a role in the pathophysiology of IBS.¹⁸ Both lymphocyte infiltration of the myenteric plexus and an increase in intestinal mucosal T lymphocytes have been observed, and it is generally accepted that the mucosal immune system seems to be activated, at least in a subset of patients with IBS.¹⁹ Irritable bowel syndrome associations with quiescent inflammatory bowel disease or postinfectious gastroenteritis provide 2 potential causes for the inflammation, but most IBS patients have had neither.²⁰ The mucosal lining of the intestine and immune system have vast exposure to intraluminal allergens in transit, and it is hypothesized that the same delayed-type hypersensitivity response elicited in the skin by patch testing is elicited in the intestine, resulting in the inflammation that triggers IBS symptoms.¹⁰ The results here add to the growing body of evidence that ingestion of type IV food allergens by previously sensitized individuals could, in fact, be the primary source of the inflammation observed in a large subpopulation of individuals who carry a diagnosis of IBS.

Food Allergens in Patch Testing
Many of the food allergens used in this study are commonly found in various nonfood products that may contact the skin. For example, many flavorings are used as fragrances, and many preservatives, binders, thickeners, emulsifiers, and stabilizers serve the same role in moisturizers, cosmetics, and topical medications. Likewise, nickel sulfate hexahydrate, ubiquitous in foods that arise from the earth, often is found in metal in jewelry, clothing components, and cell phones. All are potential sensitizers. Thus, the question may arise whether the causal relationship between the food allergens identified by patch testing and IBS symptoms might be more of a systemic effect akin to systemic contact dermatitis as sometimes follows ingestion of an allergen to which an individual has been topically sensitized, rather than the proposed localized immunologic response in the intestinal lining. We were unaware of patient history of allergic contact dermatitis to any of the patch test allergens in this study, but the dermatologist author here (M.S.) has unpublished experience with 2 other patients with IBS who have benefited from low-nickel diets after having had positive patch tests to nickel sulfate hexahydrate and who, in retrospect, did report a history of earring dermatitis. Future investigations using pre– and post–food challenge histologic assessments of the intestinal mucosa in patients who benefit from patch test–guided food avoidance diets should help to better define the mechanism.

Because IBS has not been traditionally associated with structural or biochemical abnormalities detectable with current routine diagnostic tools, it has long been viewed as a functional disorder. The findings published more recently,^9,10 in addition to this study’s results, would negate this functional classification in the subset of patients with IBS symptoms who experience sustained relief of their symptoms by patch test–directed food avoidance. The underlying delayed-type hypersensitivity pathogenesis of the IBS-like symptoms in these individuals would mandate an organic classification, aptly named allergic contact enteritis.¹⁰

Follow-up Data
The mean (SD) follow-up duration for this study and the 2018 report⁹ was 4.5 (3.0) months and 7.6 (3.9) months, respectively. The placebo effect is a concern for disorders such as IBS in which primarily subjective outcome measures are available,²¹ and in a retrospective analysis of 25 randomized, placebo-controlled IBS clinical trials, Spiller²² concluded the optimum length of such trials to be more than 3 months, which these studies exceed. Although not blinded or placebo controlled, the length of follow-up in the 2018 report⁹ and here enhances the validity of the results.

Limitation
The retrospective manner in which the self-assessments were reported in this study introduces the potential for recall bias, a variable that could affect results. The presence and direction of bias by any given individual cannot be known, making it difficult to determine any effect it may have had. Further investigation should include daily assessments and refine the primary study end points to include both abdominal pain and the defecation considerations that define IBS.

Conclusion

Food patch testing has the potential to offer a safe, cost-effective approach to the evaluation and management of IBS symptoms. Randomized clinical trials are needed to further investigate the validity of the proof-of-concept results to date. For patients who benefit from a patch test–guided avoidance diet, invasive and costly endoscopic, radiologic, and laboratory testing and pharmacologic management could be averted. Symptomatic relief could be attained simply by avoiding the implicated foods, essentially doing more by doing less. 


Irritable bowel syndrome (IBS) is one of the most common disorders managed by primary care physicians and gastroenterologists.¹ Characterized by abdominal pain coinciding with altered stool form and/or frequency as defined by the Rome IV diagnostic criteria,² symptoms range from mild to debilitating and may remarkably impair quality of life and work productivity.¹

The cause of IBS is poorly understood. Proposed pathophysiologic factors include impaired mucosal function, microbial imbalance, visceral hypersensitivity, psychologic dysfunction, genetic factors, neurotransmitter imbalance, postinfectious gastroenteritis, inflammation, and food intolerance, any or all of which may lead to the development and maintenance of IBS symptoms.³ More recent observations of inflammation in the intestinal lining^4,5 and proinflammatory peripherally circulating cytokines⁶ challenge its traditional classification as a functional disorder.

The cause of this inflammation is of intense interest, with speculation that the bacterial microbiota, bile acids, association with postinfectious gastroenteritis and inflammatory bowel disease cases, and/or foods may contribute. Although approximately 50% of individuals with IBS report that foods aggravate their symptoms,⁷ studies investigating type I antibody–mediated immediate hypersensitivity have largely failed to demonstrate a substantial link, prompting many authorities to regard these associations as food “intolerances” rather than true allergies. Based on this body of literature, a large 2010 consensus report on all aspects of food allergies advises against food allergy testing for IBS.⁸

In contrast, by utilizing type IV food allergen skin patch testing, 2 proof-of-concept studies^9,10 investigated a different allergic mechanism in IBS, namely cell-mediated delayed-type hypersensitivity. Because many foods and food additives are known to cause allergic contact dermatitis,¹¹ it was hypothesized that these foods may elicit a similar delayed-type hypersensitivity response in the intestinal lining in previously sensitized individuals. By following a patch test–guided food avoidance diet, a large subpopulation of patients with IBS experienced partial or complete IBS symptom relief.^9,10 Our study further investigates a role for food-related delayed-type hypersensitivities in the pathogenesis of IBS.

Methods

Patient Selection
This study was conducted in a secondary care community-based setting. All patients were self-referred over an 18-month period ending in October 2019, had physician-diagnosed IBS, and/or met the Rome IV criteria for IBS and presented expressly for the food patch testing on a fee-for-service basis. Subtype of IBS was determined on presentation by the self-reported historically predominant symptom. Duration of IBS symptoms was self-reported and was rounded to the nearest year for purposes of data collection.

Exclusion criteria included pregnancy, known allergy to adhesive tape or any of the food allergens used in the study, severe skin rash, symptoms that had a known cause other than IBS, or active treatment with systemic immunosuppressive medications.

Patch Testing
Skin patch testing was initiated using an extensive panel of 117 type IV food allergens (eTable)¹¹ identified in the literature,¹² most of which utilized standard compounded formulations¹³ or were available from reputable patch test manufacturers (Brial Allergen GmbH; Chemotechnique Diagnostics). This panel was not approved by the US Food and Drug Administration. The freeze-dried vegetable formulations were taken from the 2018 report.⁹ Standard skin patch test procedure protocols¹² were used, affixing the patches to the upper aspect of the back.

Following patch test application on day 1, two follow-up visits occurred on day 3 and either day 4 or day 5. On day 3, patches were removed, and the initial results were read by a board-certified dermatologist according to a standard grading system.¹⁴ Interpretation of patch tests included no reaction, questionable reaction consisting of macular erythema, weak reaction consisting of erythema and slight edema, or strong reaction consisting of erythema and marked edema. On day 4 or day 5, the final patch test reading was performed, and patients were informed of their results. Patients were advised to avoid ingestion of all foods that elicited a questionable or positive patch test response for at least 3 months, and information about the foods and their avoidance also was distributed and reviewed.

Food Avoidance Questionnaire
Patients with questionable or positive patch tests at 72 or 96 hours were advised of their eligibility to participate in an institutional review board–approved food avoidance questionnaire study investigating the utility of patch test–guided food avoidance on IBS symptoms. The questionnaire assessed the following: (1) baseline average abdominal pain prior to patch test–guided avoidance diet (0=no symptoms; 10=very severe); (2) average abdominal pain since initiation of patch test–guided avoidance diet (0=no symptoms; 10=very severe); (3) degree of improvement in overall IBS symptoms by the end of the food avoidance period (0=no improvement; 10=great improvement); (4) compliance with the avoidance diet for the duration of the avoidance period (completely, partially, not at all, or not sure).

Questionnaires and informed consent were mailed to patients via the US Postal Service 3 months after completing the patch testing. The questionnaire and consent were to be completed and returned after dietary avoidance of the identified allergens for at least 3 months. Patients were not compensated for participation in the study.

Statistical Analysis
Statistical analysis of data collected from study questionnaires was performed with Microsoft Excel. Mean abdominal pain and mean global improvement scores were reported along with 1 SD of the mean. For comparison of mean abdominal pain and improvement in global IBS symptoms from baseline to after 3 months of identified allergen avoidance, a Mann-Whitney U test was performed, with P<.05 being considered statistically significant.

Results

Thirty-seven consecutive patients underwent the testing and were eligible for the study. Nineteen patients were included in the study by virtue of completing and returning their posttest food avoidance questionnaire and informed consent. Eighteen patients were White and 1 was Asian. Subcategories of IBS were diarrhea predominant (9 [47.4%]), constipation predominant (3 [15.8%]), mixed type (5 [26.3%]), and undetermined type (2 [10.5%]). Questionnaire answers were reported after a mean (SD) duration of patch test–directed food avoidance of 4.5 (3.0) months (Table 1).

Overall Improvement
Fifteen (78.9%) patients reported at least slight to great improvement in their global IBS symptoms, and 4 (21.1%) reported no improvement (Table 2), with a mean (SD) improvement score of 5.1 (3.3)(P<.00001).

Comment

Despite intense research interest and a growing number of new medications for IBS approved by the US Food and Drug Administration, there remains a large void in the search for cost-effective and efficacious approaches for IBS evaluation and treatment. In addition to major disturbances in quality of life,^14,15 the cost to society in direct medical expenses and indirect costs associated with loss of productivity and work absenteeism is considerable; estimates range from $21 billion or more annually.¹⁶

Food Hypersensitivities Triggering IBS
This study further evaluated a role for skin patch testing to identify delayed-type (type IV) food hypersensitivities that trigger IBS symptoms and differed from the prior investigations^9,10 in that the symptoms used to define IBS were updated from the Rome III¹⁷ to the newer Rome IV² criteria. The data presented here show moderate to great improvement in global IBS symptoms in 58% (11/19) of patients, which is in line with a 2018 report of 40 study participants for whom follow-up at 3 or more months was available,⁹ providing additional support for a role for type IV food allergies in causing the same gastrointestinal tract symptoms that define IBS. The distinction between food-related studies, including this one, that implicate food allergies^9,10 and prior studies that did not support a role for food allergies in IBS pathogenesis⁸ can be accounted for by the type of allergy investigated. Conclusions that IBS flares after food ingestion were attributable to intolerance rather than true allergy were based on results investigating only the humoral arm and failed to consider the cell-mediated arm of the immune system. As such, foods that appear to trigger IBS symptoms on an allergic basis in our study are recognized in the literature¹² as type IV allergens that elicit cell-mediated immunologic responses rather than more widely recognized type I allergens, such as peanuts and shellfish, that elicit immediate-type hypersensitivity responses. Although any type IV food allergen(s) could be responsible, a pattern emerged in this study and the study published in 2018.⁹ Namely, some foods stood out as more frequently inducing patch test reactions, with the 3 most common being carmine, cinnamon bark oil, and sodium bisulfite (eTable). The sample size is relatively small, but the results raise the question of whether these foods are the most likely to trigger IBS symptoms in the general population. If so, is it the result of a higher innate sensitizing potential and/or a higher frequency of exposure in commonly eaten foods? Larger randomized clinical trials are needed.

Immune Response and IBS
There is mounting evidence that the immune system may play a role in the pathophysiology of IBS.¹⁸ Both lymphocyte infiltration of the myenteric plexus and an increase in intestinal mucosal T lymphocytes have been observed, and it is generally accepted that the mucosal immune system seems to be activated, at least in a subset of patients with IBS.¹⁹ Irritable bowel syndrome associations with quiescent inflammatory bowel disease or postinfectious gastroenteritis provide 2 potential causes for the inflammation, but most IBS patients have had neither.²⁰ The mucosal lining of the intestine and immune system have vast exposure to intraluminal allergens in transit, and it is hypothesized that the same delayed-type hypersensitivity response elicited in the skin by patch testing is elicited in the intestine, resulting in the inflammation that triggers IBS symptoms.¹⁰ The results here add to the growing body of evidence that ingestion of type IV food allergens by previously sensitized individuals could, in fact, be the primary source of the inflammation observed in a large subpopulation of individuals who carry a diagnosis of IBS.

Food Allergens in Patch Testing
Many of the food allergens used in this study are commonly found in various nonfood products that may contact the skin. For example, many flavorings are used as fragrances, and many preservatives, binders, thickeners, emulsifiers, and stabilizers serve the same role in moisturizers, cosmetics, and topical medications. Likewise, nickel sulfate hexahydrate, ubiquitous in foods that arise from the earth, often is found in metal in jewelry, clothing components, and cell phones. All are potential sensitizers. Thus, the question may arise whether the causal relationship between the food allergens identified by patch testing and IBS symptoms might be more of a systemic effect akin to systemic contact dermatitis as sometimes follows ingestion of an allergen to which an individual has been topically sensitized, rather than the proposed localized immunologic response in the intestinal lining. We were unaware of patient history of allergic contact dermatitis to any of the patch test allergens in this study, but the dermatologist author here (M.S.) has unpublished experience with 2 other patients with IBS who have benefited from low-nickel diets after having had positive patch tests to nickel sulfate hexahydrate and who, in retrospect, did report a history of earring dermatitis. Future investigations using pre– and post–food challenge histologic assessments of the intestinal mucosa in patients who benefit from patch test–guided food avoidance diets should help to better define the mechanism.

Because IBS has not been traditionally associated with structural or biochemical abnormalities detectable with current routine diagnostic tools, it has long been viewed as a functional disorder. The findings published more recently,^9,10 in addition to this study’s results, would negate this functional classification in the subset of patients with IBS symptoms who experience sustained relief of their symptoms by patch test–directed food avoidance. The underlying delayed-type hypersensitivity pathogenesis of the IBS-like symptoms in these individuals would mandate an organic classification, aptly named allergic contact enteritis.¹⁰

Follow-up Data
The mean (SD) follow-up duration for this study and the 2018 report⁹ was 4.5 (3.0) months and 7.6 (3.9) months, respectively. The placebo effect is a concern for disorders such as IBS in which primarily subjective outcome measures are available,²¹ and in a retrospective analysis of 25 randomized, placebo-controlled IBS clinical trials, Spiller²² concluded the optimum length of such trials to be more than 3 months, which these studies exceed. Although not blinded or placebo controlled, the length of follow-up in the 2018 report⁹ and here enhances the validity of the results.

Limitation
The retrospective manner in which the self-assessments were reported in this study introduces the potential for recall bias, a variable that could affect results. The presence and direction of bias by any given individual cannot be known, making it difficult to determine any effect it may have had. Further investigation should include daily assessments and refine the primary study end points to include both abdominal pain and the defecation considerations that define IBS.

Conclusion

Food patch testing has the potential to offer a safe, cost-effective approach to the evaluation and management of IBS symptoms. Randomized clinical trials are needed to further investigate the validity of the proof-of-concept results to date. For patients who benefit from a patch test–guided avoidance diet, invasive and costly endoscopic, radiologic, and laboratory testing and pharmacologic management could be averted. Symptomatic relief could be attained simply by avoiding the implicated foods, essentially doing more by doing less. 


The COVID-19 pandemic has overwhelmed health care facilities and health care providers (HCPs) due to the limited resources available to treat a rapidly expanding patient population. Health care providers have been required to work long hours and put themselves at increased risk of infection by coming into frequent contact with infected patients. In addition to the risk of becoming infected with severe acute respiratory syndrome coronavirus 2, HCPs might be required to wear personal protective equipment (PPE) for the entirety of the workday, which can cause a variety of adverse effects.

During the COVID-19 pandemic, there has been an increase in reported cases of facial acne, pressure injury, urticaria, allergic contact dermatitis (ACD), irritant contact dermatitis (ICD), and exacerbation of underlying cutaneous conditions among health care workers.^1-4 This increase in dermatologic disorders among HCPs has been associated with the increased utilization of and duration of exposure to PPE—particularly N95 respirator masks and surgical masks.^5-7 Most studies of these reactions have attributed them to local pressure, friction, hyperhydration, elevated pH, and occlusion caused by prolonged wearing of the masks, resulting ultimately in acne and other rashes^8-10; however, a few studies have suggested that formaldehyde is a potential culprit underlying the increase in skin reactions to face masks.^11-14

Formaldehyde is a known skin irritant and has been found to cause ACD and ICD from exposure to textiles and cosmetics treated with this chemical.^15-18 Both N95 and surgical masks previously have been found to contain sufficient levels of formaldehyde or formaldehyde-releasing resins (FRRs) to induce ACD or ICD in susceptible people.^12-14 In this article, we focus on the role of formaldehyde in N95 masks as a potential cause of ACD and ICD in HCPs who have been wearing PPE during the COVID-19 pandemic.

Formaldehyde: Benefits With Significant Problems

Formaldehyde is nearly ubiquitous in the textile industry because it confers advantageous properties, including resistance to flames, water, and wrinkling.¹⁵ Despite these advantages, it has long been established that consumers can become sensitized to formaldehyde and FRRs in textiles after chronic exposure.^15-18

A study of Australian HCPs found that 5.2% of those tested had ACD in response to formaldehyde, which was attributed to their PPE.¹¹ In a case report of ACD caused by FRRs, Donovan and Skotnicki-Grant¹² suggested that individuals who are sensitive to formaldehyde are vulnerable to reactions that are exacerbated by friction, warmth, moisture, and tight-fitting materials—all of which can occur when wearing an N95 mask. In that report, a formaldehyde-sensitive patient had a strong positive reaction on patch testing to melamine formaldehyde and to a piece of her N95 mask while taking prednisone 8 mg/d, suggesting that some sensitized patients have a strong reaction to their mask even when they are immunosuppressed.¹²

This finding, along with the known formaldehyde content of some N95 masks, suggests that these masks might be a cause of contact dermatitis in some HCPs. Somewhat complicating the situation is that false-negative patch testing can occur in and might contribute to the underdiagnosis of formaldehyde-induced N95 mask facial dermatitis.^12,13 Some HCPs have reported mild respiratory symptoms and eye irritation associated with the use of an N95 mask—symptoms that are consistent with formaldehyde exposure. In some cases, those symptoms have caused discomfort sufficient to prompt HCPs to take leave from work.^13,14

Development of contact dermatitis in response to an N95 mask is not novel; this problem also was observed during the severe acute respiratory syndrome pandemic of the early 2000s.^9,17 Some HCPs noticed onset of skin reactions after they were required to wear an N95 mask in the workplace, which some studies attributed to material in the mask increasing the likelihood of developing an adverse reaction.^2,6,8 The components of N95 masks and the materials from which they are manufactured are listed in the Table.¹⁹

Face Masks, Adverse Reactions, and Formaldehyde

Allergic contact dermatitis and ICD typically are rare responses to wearing facial masks, but the recent COVID-19 pandemic has forced HCPs to wear masks for longer than 6 hours at a time and to reuse a single mask, which has been shown to increase the likelihood of adverse reactions.^1,4,6 Additionally, humid environments, tight-fitting materials, and skin abrasions—all of which can be induced by wearing an N95 mask—have been found to increase the likelihood of formaldehyde-related contact dermatitis by increasing the release of free formaldehyde or by enhancing its penetration into the skin.^6,20,21

Formaldehyde is an ubiquitous chemical agent that is part of indoor and outdoor working and residential environments. Health care professionals have many opportunities to be exposed to formaldehyde, which is a well-known mucous membrane irritant and a primary skin-sensitizing agent associated with both contact dermatitis (type IV hypersensitivity reaction), and an immediate anaphylactic reaction (type I hypersensitivity reaction).^22-25 Exposure to formaldehyde by inhalation has been identified as a potential cause of asthma.^26,27 More studies on the prevalence of formaldehyde-induced hypersensitivity reactions would be beneficial to HCPs for early diagnosis of hypersensitivity, adequate prophylaxis, and occupational risk assessment.

N95 mask dermatitis also heightens the potential for breaches of PPE protocols. The discomfort that HCPs experience in response to adverse skin reactions to masks can cause an increased rate of inappropriate mask-wearing, face-touching during mask adjustment, and removal of the mask in the health care setting.²⁸ These acts of face-touching and PPE adjustment have been shown to increase microbial transmission and to reduce the efficacy of PPE in blocking pathogens.^29,30

Considering the mounting evidence that widespread use of masks effectively prevents viral transmission, it is crucial that all HCPs wear appropriate PPE when treating patients during the COVID-19 pandemic.^31,32 The recent surge in ACD and ICD among HCPs in response to wearing N95 masks creates a need to determine the underlying cause of these dermatoses and find methods of mitigating sensitization of HCPs to the offending agents. The current epidemiology of COVID-19 in the United States suggests that PPE will be necessary for much longer than originally anticipated and will continue to be worn for long hours by HCPs.

Formaldehyde-Free Alternatives?

Some researchers have proposed that using materials that are free of allergens like formaldehyde might be a long-term solution to the development of contact dermatitis.^15,33 Formaldehyde is used in the finishing process of N95 masks for wrinkle and crease resistance and to prevent mildew. It is possible that formaldehyde could be completely removed from the manufacturing process, although no studies on the effects of such alternatives on mask efficacy have been performed.

Formaldehyde-free alternatives that would confer similar properties on textiles have been explored; the most promising alternative to formaldehyde in cross-linking cellulose fibers is polycarboxylic acid in combination with sodium hypophosphite, which can help avoid the adverse health outcomes and environmental impact of formaldehyde.^34-36 Studies of such alternatives in the manufacturing of N95 masks would be needed to establish the efficacy and durability of formaldehyde-free PPE.

Final Thoughts

Additional studies are needed to confirm the presence of formaldehyde in N95 masks and to confirm that the mask material yields a positive patch test in sensitized individuals. The paucity of available studies that quantify formaldehyde or FRR content of N95 and surgical masks makes it difficult to establish an association between the chemical content of masks and the prevalence of mask dermatitis among HCPs; however, available reports of skin reactions, including contact dermatitis, from PPE suggest that formaldehyde sensitivity might be at least part of the problem. As such, we propose that manufacturers of N95 and surgical masks be required to reveal the chemical components of their products so that consumers can make educated purchasing decisions.

The COVID-19 pandemic has overwhelmed health care facilities and health care providers (HCPs) due to the limited resources available to treat a rapidly expanding patient population. Health care providers have been required to work long hours and put themselves at increased risk of infection by coming into frequent contact with infected patients. In addition to the risk of becoming infected with severe acute respiratory syndrome coronavirus 2, HCPs might be required to wear personal protective equipment (PPE) for the entirety of the workday, which can cause a variety of adverse effects.

During the COVID-19 pandemic, there has been an increase in reported cases of facial acne, pressure injury, urticaria, allergic contact dermatitis (ACD), irritant contact dermatitis (ICD), and exacerbation of underlying cutaneous conditions among health care workers.^1-4 This increase in dermatologic disorders among HCPs has been associated with the increased utilization of and duration of exposure to PPE—particularly N95 respirator masks and surgical masks.^5-7 Most studies of these reactions have attributed them to local pressure, friction, hyperhydration, elevated pH, and occlusion caused by prolonged wearing of the masks, resulting ultimately in acne and other rashes^8-10; however, a few studies have suggested that formaldehyde is a potential culprit underlying the increase in skin reactions to face masks.^11-14

Formaldehyde is a known skin irritant and has been found to cause ACD and ICD from exposure to textiles and cosmetics treated with this chemical.^15-18 Both N95 and surgical masks previously have been found to contain sufficient levels of formaldehyde or formaldehyde-releasing resins (FRRs) to induce ACD or ICD in susceptible people.^12-14 In this article, we focus on the role of formaldehyde in N95 masks as a potential cause of ACD and ICD in HCPs who have been wearing PPE during the COVID-19 pandemic.

Formaldehyde: Benefits With Significant Problems

Formaldehyde is nearly ubiquitous in the textile industry because it confers advantageous properties, including resistance to flames, water, and wrinkling.¹⁵ Despite these advantages, it has long been established that consumers can become sensitized to formaldehyde and FRRs in textiles after chronic exposure.^15-18

A study of Australian HCPs found that 5.2% of those tested had ACD in response to formaldehyde, which was attributed to their PPE.¹¹ In a case report of ACD caused by FRRs, Donovan and Skotnicki-Grant¹² suggested that individuals who are sensitive to formaldehyde are vulnerable to reactions that are exacerbated by friction, warmth, moisture, and tight-fitting materials—all of which can occur when wearing an N95 mask. In that report, a formaldehyde-sensitive patient had a strong positive reaction on patch testing to melamine formaldehyde and to a piece of her N95 mask while taking prednisone 8 mg/d, suggesting that some sensitized patients have a strong reaction to their mask even when they are immunosuppressed.¹²

This finding, along with the known formaldehyde content of some N95 masks, suggests that these masks might be a cause of contact dermatitis in some HCPs. Somewhat complicating the situation is that false-negative patch testing can occur in and might contribute to the underdiagnosis of formaldehyde-induced N95 mask facial dermatitis.^12,13 Some HCPs have reported mild respiratory symptoms and eye irritation associated with the use of an N95 mask—symptoms that are consistent with formaldehyde exposure. In some cases, those symptoms have caused discomfort sufficient to prompt HCPs to take leave from work.^13,14

Development of contact dermatitis in response to an N95 mask is not novel; this problem also was observed during the severe acute respiratory syndrome pandemic of the early 2000s.^9,17 Some HCPs noticed onset of skin reactions after they were required to wear an N95 mask in the workplace, which some studies attributed to material in the mask increasing the likelihood of developing an adverse reaction.^2,6,8 The components of N95 masks and the materials from which they are manufactured are listed in the Table.¹⁹

Face Masks, Adverse Reactions, and Formaldehyde

Allergic contact dermatitis and ICD typically are rare responses to wearing facial masks, but the recent COVID-19 pandemic has forced HCPs to wear masks for longer than 6 hours at a time and to reuse a single mask, which has been shown to increase the likelihood of adverse reactions.^1,4,6 Additionally, humid environments, tight-fitting materials, and skin abrasions—all of which can be induced by wearing an N95 mask—have been found to increase the likelihood of formaldehyde-related contact dermatitis by increasing the release of free formaldehyde or by enhancing its penetration into the skin.^6,20,21

Formaldehyde is an ubiquitous chemical agent that is part of indoor and outdoor working and residential environments. Health care professionals have many opportunities to be exposed to formaldehyde, which is a well-known mucous membrane irritant and a primary skin-sensitizing agent associated with both contact dermatitis (type IV hypersensitivity reaction), and an immediate anaphylactic reaction (type I hypersensitivity reaction).^22-25 Exposure to formaldehyde by inhalation has been identified as a potential cause of asthma.^26,27 More studies on the prevalence of formaldehyde-induced hypersensitivity reactions would be beneficial to HCPs for early diagnosis of hypersensitivity, adequate prophylaxis, and occupational risk assessment.

N95 mask dermatitis also heightens the potential for breaches of PPE protocols. The discomfort that HCPs experience in response to adverse skin reactions to masks can cause an increased rate of inappropriate mask-wearing, face-touching during mask adjustment, and removal of the mask in the health care setting.²⁸ These acts of face-touching and PPE adjustment have been shown to increase microbial transmission and to reduce the efficacy of PPE in blocking pathogens.^29,30

Considering the mounting evidence that widespread use of masks effectively prevents viral transmission, it is crucial that all HCPs wear appropriate PPE when treating patients during the COVID-19 pandemic.^31,32 The recent surge in ACD and ICD among HCPs in response to wearing N95 masks creates a need to determine the underlying cause of these dermatoses and find methods of mitigating sensitization of HCPs to the offending agents. The current epidemiology of COVID-19 in the United States suggests that PPE will be necessary for much longer than originally anticipated and will continue to be worn for long hours by HCPs.

Formaldehyde-Free Alternatives?

Some researchers have proposed that using materials that are free of allergens like formaldehyde might be a long-term solution to the development of contact dermatitis.^15,33 Formaldehyde is used in the finishing process of N95 masks for wrinkle and crease resistance and to prevent mildew. It is possible that formaldehyde could be completely removed from the manufacturing process, although no studies on the effects of such alternatives on mask efficacy have been performed.

Formaldehyde-free alternatives that would confer similar properties on textiles have been explored; the most promising alternative to formaldehyde in cross-linking cellulose fibers is polycarboxylic acid in combination with sodium hypophosphite, which can help avoid the adverse health outcomes and environmental impact of formaldehyde.^34-36 Studies of such alternatives in the manufacturing of N95 masks would be needed to establish the efficacy and durability of formaldehyde-free PPE.

Final Thoughts

Additional studies are needed to confirm the presence of formaldehyde in N95 masks and to confirm that the mask material yields a positive patch test in sensitized individuals. The paucity of available studies that quantify formaldehyde or FRR content of N95 and surgical masks makes it difficult to establish an association between the chemical content of masks and the prevalence of mask dermatitis among HCPs; however, available reports of skin reactions, including contact dermatitis, from PPE suggest that formaldehyde sensitivity might be at least part of the problem. As such, we propose that manufacturers of N95 and surgical masks be required to reveal the chemical components of their products so that consumers can make educated purchasing decisions.

The COVID-19 pandemic has overwhelmed health care facilities and health care providers (HCPs) due to the limited resources available to treat a rapidly expanding patient population. Health care providers have been required to work long hours and put themselves at increased risk of infection by coming into frequent contact with infected patients. In addition to the risk of becoming infected with severe acute respiratory syndrome coronavirus 2, HCPs might be required to wear personal protective equipment (PPE) for the entirety of the workday, which can cause a variety of adverse effects.

During the COVID-19 pandemic, there has been an increase in reported cases of facial acne, pressure injury, urticaria, allergic contact dermatitis (ACD), irritant contact dermatitis (ICD), and exacerbation of underlying cutaneous conditions among health care workers.^1-4 This increase in dermatologic disorders among HCPs has been associated with the increased utilization of and duration of exposure to PPE—particularly N95 respirator masks and surgical masks.^5-7 Most studies of these reactions have attributed them to local pressure, friction, hyperhydration, elevated pH, and occlusion caused by prolonged wearing of the masks, resulting ultimately in acne and other rashes^8-10; however, a few studies have suggested that formaldehyde is a potential culprit underlying the increase in skin reactions to face masks.^11-14

Formaldehyde is a known skin irritant and has been found to cause ACD and ICD from exposure to textiles and cosmetics treated with this chemical.^15-18 Both N95 and surgical masks previously have been found to contain sufficient levels of formaldehyde or formaldehyde-releasing resins (FRRs) to induce ACD or ICD in susceptible people.^12-14 In this article, we focus on the role of formaldehyde in N95 masks as a potential cause of ACD and ICD in HCPs who have been wearing PPE during the COVID-19 pandemic.

Formaldehyde: Benefits With Significant Problems

Formaldehyde is nearly ubiquitous in the textile industry because it confers advantageous properties, including resistance to flames, water, and wrinkling.¹⁵ Despite these advantages, it has long been established that consumers can become sensitized to formaldehyde and FRRs in textiles after chronic exposure.^15-18

A study of Australian HCPs found that 5.2% of those tested had ACD in response to formaldehyde, which was attributed to their PPE.¹¹ In a case report of ACD caused by FRRs, Donovan and Skotnicki-Grant¹² suggested that individuals who are sensitive to formaldehyde are vulnerable to reactions that are exacerbated by friction, warmth, moisture, and tight-fitting materials—all of which can occur when wearing an N95 mask. In that report, a formaldehyde-sensitive patient had a strong positive reaction on patch testing to melamine formaldehyde and to a piece of her N95 mask while taking prednisone 8 mg/d, suggesting that some sensitized patients have a strong reaction to their mask even when they are immunosuppressed.¹²

This finding, along with the known formaldehyde content of some N95 masks, suggests that these masks might be a cause of contact dermatitis in some HCPs. Somewhat complicating the situation is that false-negative patch testing can occur in and might contribute to the underdiagnosis of formaldehyde-induced N95 mask facial dermatitis.^12,13 Some HCPs have reported mild respiratory symptoms and eye irritation associated with the use of an N95 mask—symptoms that are consistent with formaldehyde exposure. In some cases, those symptoms have caused discomfort sufficient to prompt HCPs to take leave from work.^13,14

Development of contact dermatitis in response to an N95 mask is not novel; this problem also was observed during the severe acute respiratory syndrome pandemic of the early 2000s.^9,17 Some HCPs noticed onset of skin reactions after they were required to wear an N95 mask in the workplace, which some studies attributed to material in the mask increasing the likelihood of developing an adverse reaction.^2,6,8 The components of N95 masks and the materials from which they are manufactured are listed in the Table.¹⁹

Face Masks, Adverse Reactions, and Formaldehyde

Allergic contact dermatitis and ICD typically are rare responses to wearing facial masks, but the recent COVID-19 pandemic has forced HCPs to wear masks for longer than 6 hours at a time and to reuse a single mask, which has been shown to increase the likelihood of adverse reactions.^1,4,6 Additionally, humid environments, tight-fitting materials, and skin abrasions—all of which can be induced by wearing an N95 mask—have been found to increase the likelihood of formaldehyde-related contact dermatitis by increasing the release of free formaldehyde or by enhancing its penetration into the skin.^6,20,21

Formaldehyde is an ubiquitous chemical agent that is part of indoor and outdoor working and residential environments. Health care professionals have many opportunities to be exposed to formaldehyde, which is a well-known mucous membrane irritant and a primary skin-sensitizing agent associated with both contact dermatitis (type IV hypersensitivity reaction), and an immediate anaphylactic reaction (type I hypersensitivity reaction).^22-25 Exposure to formaldehyde by inhalation has been identified as a potential cause of asthma.^26,27 More studies on the prevalence of formaldehyde-induced hypersensitivity reactions would be beneficial to HCPs for early diagnosis of hypersensitivity, adequate prophylaxis, and occupational risk assessment.

N95 mask dermatitis also heightens the potential for breaches of PPE protocols. The discomfort that HCPs experience in response to adverse skin reactions to masks can cause an increased rate of inappropriate mask-wearing, face-touching during mask adjustment, and removal of the mask in the health care setting.²⁸ These acts of face-touching and PPE adjustment have been shown to increase microbial transmission and to reduce the efficacy of PPE in blocking pathogens.^29,30

Considering the mounting evidence that widespread use of masks effectively prevents viral transmission, it is crucial that all HCPs wear appropriate PPE when treating patients during the COVID-19 pandemic.^31,32 The recent surge in ACD and ICD among HCPs in response to wearing N95 masks creates a need to determine the underlying cause of these dermatoses and find methods of mitigating sensitization of HCPs to the offending agents. The current epidemiology of COVID-19 in the United States suggests that PPE will be necessary for much longer than originally anticipated and will continue to be worn for long hours by HCPs.

Formaldehyde-Free Alternatives?

Some researchers have proposed that using materials that are free of allergens like formaldehyde might be a long-term solution to the development of contact dermatitis.^15,33 Formaldehyde is used in the finishing process of N95 masks for wrinkle and crease resistance and to prevent mildew. It is possible that formaldehyde could be completely removed from the manufacturing process, although no studies on the effects of such alternatives on mask efficacy have been performed.

Formaldehyde-free alternatives that would confer similar properties on textiles have been explored; the most promising alternative to formaldehyde in cross-linking cellulose fibers is polycarboxylic acid in combination with sodium hypophosphite, which can help avoid the adverse health outcomes and environmental impact of formaldehyde.^34-36 Studies of such alternatives in the manufacturing of N95 masks would be needed to establish the efficacy and durability of formaldehyde-free PPE.

Final Thoughts

Additional studies are needed to confirm the presence of formaldehyde in N95 masks and to confirm that the mask material yields a positive patch test in sensitized individuals. The paucity of available studies that quantify formaldehyde or FRR content of N95 and surgical masks makes it difficult to establish an association between the chemical content of masks and the prevalence of mask dermatitis among HCPs; however, available reports of skin reactions, including contact dermatitis, from PPE suggest that formaldehyde sensitivity might be at least part of the problem. As such, we propose that manufacturers of N95 and surgical masks be required to reveal the chemical components of their products so that consumers can make educated purchasing decisions.

Identifying safe, effective, and affordable evidence-based dermatologic treatments for older adults can be challenging because of age-related changes in the skin, comorbidities, polypharmacy, mobility issues, and cognitive changes. Phototherapy has been shown to be an effective nonpharmacologic treatment option for multiple challenging dermatologic conditions^1-8; however, few studies have specifically examined its effectiveness in older adults. The challenge for older patients with psoriasis and dermatitis is that the conditions can be difficult to control and often require multiple treatment modalities.^9,10 Patients with psoriasis also have a higher risk for diabetes, dyslipidemia, and cardiovascular disease compared to other older patients,^11,12 which poses treatment challenges and makes nonpharmacologic treatments even more appealing.

Recent studies show that phototherapy can help decrease the use of dermatologic medications. Foerster and colleagues² found that adults with psoriasis who were treated with phototherapy significantly decreased their use of topical steroids (24.5% fewer patients required steroid creams and 31.1% fewer patients required psoriasis-specific topicals)(P<.01) while their use of non–psoriasis-specific medications did not change. Click and colleagues¹³ identified a decrease in medication costs, health care utilization, and risk for immunosuppression in patients treated with phototherapy when compared to those treated with biologics and apremilast. Methotrexate is a common dermatologic medication that is highly associated with increased risks in elderly patients because of impaired immune system function and the presence of comorbidities (eg, kidney disease, obesity, diabetes, fatty liver),¹⁴ which increase in prevalence with age. Combining phototherapy with methotrexate can substantially decrease the amount of methotrexate needed to achieve disease control,¹⁵ thereby decreasing the methotrexate-associated risks. Findings from these studies suggest that a safe, effective, cost-effective, and well-tolerated nonpharmacologic alternative, such as phototherapy, is highly desirable and should be optimized. Unfortunately, most studies that report the effectiveness of phototherapy are in younger populations.

This retrospective study aimed to (1) identify the most common dermatologic conditions treated with phototherapy in older adults, (2) examine the effectiveness and safety of phototherapy in older adults, and (3) compare the outcomes with 2 similar studies in the United Kingdom¹⁶ and Turkey.¹⁷

Methods

Design, Setting, Sample, and Statistical Analysis
The institutional review boards of Kaiser Permanente Washington Health Research Institute, Seattle, and the University of Washington, Seattle, approved this study. It was conducted in a large US multispecialty health care system (Group Health, Seattle, Washington [now Kaiser Permanente Washington]) serving approximately 600,000 patients, using billing records to identify all patients treated with phototherapy between January 1, 2015, and December 31, 2015, all who received narrowband UVB (NB-UVB) phototherapy. All adults 65 years and older who received phototherapy treatment during the 12-month study period were included. Patients were included regardless of comorbidities and other dermatologic treatments to maintain as much uniformity as possible between the present study and 2 prior studies examining phototherapy in older adult populations in the United Kingdom¹⁶ and Turkey.¹⁷ Demographic and clinical factors were presented using frequencies (percentages) or means and medians as appropriate. Comparisons of dermatologic conditions and clearance levels used a Fisher exact test. The number of phototherapy treatments to clearance and total number of treatments were compared between groups of patients using independent sample t tests.

Phototherapy Protocol
All patients received treatments administered by specially trained phototherapy nurses using a Daavlin UV Series (The Daavlin Company) or an Ultralite unit (Ultralite Enterprises, Inc), both with 48 lamps. All phototherapy nurses had been previously trained to provide treatments based on standardized protocols (Table 1) and to determine the patient’s level of disease clearance using a high to low clearance scale (Table 2). Daavlin’s treatment protocols were built into the software that accompanied the units and were developed based on the American Academy of Dermatology guidelines. The starting dose for an individual patient was determined based on the estimated minimal erythema dose for each phototype. If the patient was using photosensitizing medications, then the protocol guided the nurse to start the patient at a lower dose appropriate for their phototype. Patients with vitiligo were treated with the same starting and escalation doses as patients with Fitzpatrick phototype I because of the assumption that their vitiliginous skin had an increased risk for photosensitivity. A more recent review of the evidence has indicated that this assumption was overly conservative,¹⁸ and Kaiser Permanente Washington’s vitiligo protocol has been adjusted.

Results

Patients
Billing records identified 229 total patients who received phototherapy in 2015, of whom 52 (22.7%) were at least 65 years old. The median age was 70 years (range, 65–91 years). Twenty-nine (56%) were men and 35 (67%) had previously received phototherapy treatments.

Dermatologic Conditions Treated With Phototherapy
Our primary aim was to identify the most common dermatologic conditions treated with phototherapy in older adults. Psoriasis and dermatitis were the most common conditions treated in the sample (50% [26/52] and 21% [11/52], respectively), with mycosis fungoides being the third most common (10% [5/52]) and vitiligo tied with prurigo nodularis as fourth most common (6% [3/52])(Figure 1).

Effectiveness and Safety of Phototherapy
Our secondary aim was to examine the effectiveness and safety of phototherapy in older adults. Phototherapy was effective in this population, with 50 of 52 patients (96%) achieving a high or medium level of clearance. The degree of clearance for each of the dermatologic conditions is shown in Figure 2. Psoriasis and dermatitis achieved high clearance rates in 81% (21/26) and 82% (9/11) of patients, respectively. Overall, conditions did not have significant differences in clearances rates (Fisher exact test, P=.10). On average, it took patients 33 treatments to achieve medium or high rates of clearance. Psoriasis cleared more quickly, with an average of 30.4 treatments vs 36.1 treatments for other conditions, but the difference was not significant (t test, P=.26). Patients received an average of 98 total phototherapy treatments; the median number of treatments was 81 due to many being on maintenance therapy over several months. There was no relationship between a history of treatment with phototherapy and the total number of treatments needed to achieve clearance (t test, P=.40), but interestingly, those who had a history of phototherapy took approximately 5 more treatments to achieve clearance. The present study found that a slightly larger number of men were being treated for psoriasis (15 men vs 11 women), but there was no significant difference in response rate based on gender.

Comment

Our study found that 94% of patients with psoriasis achieved clearance with an average of 30.4 treatments, which is comparable to the reported 91% response rate with an average of 30 treatments in the United Kingdom.¹⁶ The other similar study in Turkey¹⁷ reported 73.7% of psoriasis patients achieved a 75% or more improvement from baseline with an average of 42 treatments, which may reflect underlying differences in regional skin type. Of note, the scatter chart (Figure 3) shows that several patients in the present study’s analysis are listed as not clear, but many of those patients had low treatment numbers below the mean time to clearance. Thus, the present study’s response rate may have been underestimated.

In the general population, studies show that psoriasis treated with standardized phototherapy protocols typically clears with an average of 20.6 treatments.²¹ The levels of clearance were similar in our study’s older population, but more treatments were required to achieve those results, with an average of 10 more treatments needed (an additional 3.3 weeks). Similar results were found in this sample for dermatitis and mycosis fungoides, indicating comparable clearance rates and levels but a need for more treatments to achieve similar results compared to the general population.

Additionally, in the current study more patients experienced grade 1 (mild) erythema (46%) and grade 2 erythema (25%) at some point in their treatment compared with the United Kingdom¹⁶ (1.89%) and Turkey¹⁷ (35%) studies, though these side effects did not impact the clearance rate. Interestingly, the current study’s scatter chart (Figure 3) illustrates that this side effect did not seem to increase with aging in this population. If anything, the erythema response was more prevalent in the median or younger patients in the sample. Erythema may have been due to the frequent use of photosensitizing medications in older adults in the United States, some of which typically get discontinued in patients 75 years and older (eg, statins). Other potential causes might include the use of phototype vs minimal erythema dose–driven protocols, the standard utilization of protocols originally designed for psoriasis vs other condition-specific protocols, missed treatments leading to increased sensitivity, or possibly shielding mishaps (eg, not wearing a prescribed face shield). Given the number of potential causes and the possibility of overlapping factors, careful analysis is important. With NB-UVB phototherapy, near-erythemogenic doses are optimal to achieve effective treatments, but this delicate balance may be more problematic for older adults. Future studies are needed to fully determine the factors at play for this population. In the interim, it is important for phototherapy-trained nurses to consider this risk carefully in the older population. They must follow the prescribed protocols that guide them to query patients about their responses to the prior treatment (eg, erythema, tenderness, itching), photosensitizing medications, missed treatments, and placement of shielding, and then adjust the treatment dosing accordingly.

Limitations
This study had several limitations. Although clinical outcomes were recorded prospectively, the analysis was retrospective, unblinded, and not placebo controlled. It was conducted in a single organization (Group Health [now Kaiser Permanente Washington]) but did analyze data from 4 medical centers in different cities with diverse demographics and a variety of nursing staff providing the treatments. Although the vitiligo treatment protocol likely slowed the response rate for those patients with vitiligo, the numbers were small (ie, only 3 of 52 patients), so the researchers chose to include them in the current study. The sample population was relatively small, but when these data are evaluated alongside the studies in the United Kingdom¹⁶ and Turkey,¹⁷ they show a consistent picture illustrating the effectiveness and safety of phototherapy in the older population. Further epidemiologic studies could be helpful to further describe the usefulness of this modality compared with other treatments for a variety of dermatoses in this age group. Supplementary analysis specifically examining the relationship between the number and type of photosensitizing medications, frequency of erythema, and time to clearance also could be useful.

Conclusion

Older adults with a variety of dermatoses respond well to phototherapy and should have the opportunity to use it, particularly considering the potential for increased complications and costs from other treatment modalities, such as commonly used immunosuppressive pharmaceuticals. However, the current study and the comparison studies indicate that it is important to carefully consider the slower clearance rates and the potential risk for increased erythema in this population and adjust patient education and treatment dosing accordingly.

Unfortunately, many dermatology centers do not offer phototherapy because of infrastructure limitations such as space and specially trained nursing staff. Increasing accessibility of phototherapy for older adults through home treatments may be an alternative, given its effectiveness in the general population.^22,23 In addition, home phototherapy may be worth pursuing for the older population considering the challenges they may face with transportation to the clinic setting and their increased risk for serious illness if exposed to infections such as COVID-19. The COVID-19 pandemic has brought to light the need for reliable, safe, and effective treatments that can be utilized in the safety of patients’ homes and should therefore be considered as an option for older adults. Issues such as mobility and cognitive decline could pose some complicating factors, but with the help of a well-trained family member or caregiver, home phototherapy could be a viable option that improves accessibility for older patients. Future research opportunities include further examination of the slower but ultimately equivalent response to phototherapy in the older population, the influence of photosensitizing medications on phototherapy effects, and the impact of phototherapy on utilization of immunosuppressive pharmaceuticals in older adults.

Identifying safe, effective, and affordable evidence-based dermatologic treatments for older adults can be challenging because of age-related changes in the skin, comorbidities, polypharmacy, mobility issues, and cognitive changes. Phototherapy has been shown to be an effective nonpharmacologic treatment option for multiple challenging dermatologic conditions^1-8; however, few studies have specifically examined its effectiveness in older adults. The challenge for older patients with psoriasis and dermatitis is that the conditions can be difficult to control and often require multiple treatment modalities.^9,10 Patients with psoriasis also have a higher risk for diabetes, dyslipidemia, and cardiovascular disease compared to other older patients,^11,12 which poses treatment challenges and makes nonpharmacologic treatments even more appealing.

Recent studies show that phototherapy can help decrease the use of dermatologic medications. Foerster and colleagues² found that adults with psoriasis who were treated with phototherapy significantly decreased their use of topical steroids (24.5% fewer patients required steroid creams and 31.1% fewer patients required psoriasis-specific topicals)(P<.01) while their use of non–psoriasis-specific medications did not change. Click and colleagues¹³ identified a decrease in medication costs, health care utilization, and risk for immunosuppression in patients treated with phototherapy when compared to those treated with biologics and apremilast. Methotrexate is a common dermatologic medication that is highly associated with increased risks in elderly patients because of impaired immune system function and the presence of comorbidities (eg, kidney disease, obesity, diabetes, fatty liver),¹⁴ which increase in prevalence with age. Combining phototherapy with methotrexate can substantially decrease the amount of methotrexate needed to achieve disease control,¹⁵ thereby decreasing the methotrexate-associated risks. Findings from these studies suggest that a safe, effective, cost-effective, and well-tolerated nonpharmacologic alternative, such as phototherapy, is highly desirable and should be optimized. Unfortunately, most studies that report the effectiveness of phototherapy are in younger populations.

This retrospective study aimed to (1) identify the most common dermatologic conditions treated with phototherapy in older adults, (2) examine the effectiveness and safety of phototherapy in older adults, and (3) compare the outcomes with 2 similar studies in the United Kingdom¹⁶ and Turkey.¹⁷

Methods

Design, Setting, Sample, and Statistical Analysis
The institutional review boards of Kaiser Permanente Washington Health Research Institute, Seattle, and the University of Washington, Seattle, approved this study. It was conducted in a large US multispecialty health care system (Group Health, Seattle, Washington [now Kaiser Permanente Washington]) serving approximately 600,000 patients, using billing records to identify all patients treated with phototherapy between January 1, 2015, and December 31, 2015, all who received narrowband UVB (NB-UVB) phototherapy. All adults 65 years and older who received phototherapy treatment during the 12-month study period were included. Patients were included regardless of comorbidities and other dermatologic treatments to maintain as much uniformity as possible between the present study and 2 prior studies examining phototherapy in older adult populations in the United Kingdom¹⁶ and Turkey.¹⁷ Demographic and clinical factors were presented using frequencies (percentages) or means and medians as appropriate. Comparisons of dermatologic conditions and clearance levels used a Fisher exact test. The number of phototherapy treatments to clearance and total number of treatments were compared between groups of patients using independent sample t tests.

Phototherapy Protocol
All patients received treatments administered by specially trained phototherapy nurses using a Daavlin UV Series (The Daavlin Company) or an Ultralite unit (Ultralite Enterprises, Inc), both with 48 lamps. All phototherapy nurses had been previously trained to provide treatments based on standardized protocols (Table 1) and to determine the patient’s level of disease clearance using a high to low clearance scale (Table 2). Daavlin’s treatment protocols were built into the software that accompanied the units and were developed based on the American Academy of Dermatology guidelines. The starting dose for an individual patient was determined based on the estimated minimal erythema dose for each phototype. If the patient was using photosensitizing medications, then the protocol guided the nurse to start the patient at a lower dose appropriate for their phototype. Patients with vitiligo were treated with the same starting and escalation doses as patients with Fitzpatrick phototype I because of the assumption that their vitiliginous skin had an increased risk for photosensitivity. A more recent review of the evidence has indicated that this assumption was overly conservative,¹⁸ and Kaiser Permanente Washington’s vitiligo protocol has been adjusted.

Results

Patients
Billing records identified 229 total patients who received phototherapy in 2015, of whom 52 (22.7%) were at least 65 years old. The median age was 70 years (range, 65–91 years). Twenty-nine (56%) were men and 35 (67%) had previously received phototherapy treatments.

Dermatologic Conditions Treated With Phototherapy
Our primary aim was to identify the most common dermatologic conditions treated with phototherapy in older adults. Psoriasis and dermatitis were the most common conditions treated in the sample (50% [26/52] and 21% [11/52], respectively), with mycosis fungoides being the third most common (10% [5/52]) and vitiligo tied with prurigo nodularis as fourth most common (6% [3/52])(Figure 1).

Effectiveness and Safety of Phototherapy
Our secondary aim was to examine the effectiveness and safety of phototherapy in older adults. Phototherapy was effective in this population, with 50 of 52 patients (96%) achieving a high or medium level of clearance. The degree of clearance for each of the dermatologic conditions is shown in Figure 2. Psoriasis and dermatitis achieved high clearance rates in 81% (21/26) and 82% (9/11) of patients, respectively. Overall, conditions did not have significant differences in clearances rates (Fisher exact test, P=.10). On average, it took patients 33 treatments to achieve medium or high rates of clearance. Psoriasis cleared more quickly, with an average of 30.4 treatments vs 36.1 treatments for other conditions, but the difference was not significant (t test, P=.26). Patients received an average of 98 total phototherapy treatments; the median number of treatments was 81 due to many being on maintenance therapy over several months. There was no relationship between a history of treatment with phototherapy and the total number of treatments needed to achieve clearance (t test, P=.40), but interestingly, those who had a history of phototherapy took approximately 5 more treatments to achieve clearance. The present study found that a slightly larger number of men were being treated for psoriasis (15 men vs 11 women), but there was no significant difference in response rate based on gender.

Comment

Our study found that 94% of patients with psoriasis achieved clearance with an average of 30.4 treatments, which is comparable to the reported 91% response rate with an average of 30 treatments in the United Kingdom.¹⁶ The other similar study in Turkey¹⁷ reported 73.7% of psoriasis patients achieved a 75% or more improvement from baseline with an average of 42 treatments, which may reflect underlying differences in regional skin type. Of note, the scatter chart (Figure 3) shows that several patients in the present study’s analysis are listed as not clear, but many of those patients had low treatment numbers below the mean time to clearance. Thus, the present study’s response rate may have been underestimated.

In the general population, studies show that psoriasis treated with standardized phototherapy protocols typically clears with an average of 20.6 treatments.²¹ The levels of clearance were similar in our study’s older population, but more treatments were required to achieve those results, with an average of 10 more treatments needed (an additional 3.3 weeks). Similar results were found in this sample for dermatitis and mycosis fungoides, indicating comparable clearance rates and levels but a need for more treatments to achieve similar results compared to the general population.

Additionally, in the current study more patients experienced grade 1 (mild) erythema (46%) and grade 2 erythema (25%) at some point in their treatment compared with the United Kingdom¹⁶ (1.89%) and Turkey¹⁷ (35%) studies, though these side effects did not impact the clearance rate. Interestingly, the current study’s scatter chart (Figure 3) illustrates that this side effect did not seem to increase with aging in this population. If anything, the erythema response was more prevalent in the median or younger patients in the sample. Erythema may have been due to the frequent use of photosensitizing medications in older adults in the United States, some of which typically get discontinued in patients 75 years and older (eg, statins). Other potential causes might include the use of phototype vs minimal erythema dose–driven protocols, the standard utilization of protocols originally designed for psoriasis vs other condition-specific protocols, missed treatments leading to increased sensitivity, or possibly shielding mishaps (eg, not wearing a prescribed face shield). Given the number of potential causes and the possibility of overlapping factors, careful analysis is important. With NB-UVB phototherapy, near-erythemogenic doses are optimal to achieve effective treatments, but this delicate balance may be more problematic for older adults. Future studies are needed to fully determine the factors at play for this population. In the interim, it is important for phototherapy-trained nurses to consider this risk carefully in the older population. They must follow the prescribed protocols that guide them to query patients about their responses to the prior treatment (eg, erythema, tenderness, itching), photosensitizing medications, missed treatments, and placement of shielding, and then adjust the treatment dosing accordingly.

Limitations
This study had several limitations. Although clinical outcomes were recorded prospectively, the analysis was retrospective, unblinded, and not placebo controlled. It was conducted in a single organization (Group Health [now Kaiser Permanente Washington]) but did analyze data from 4 medical centers in different cities with diverse demographics and a variety of nursing staff providing the treatments. Although the vitiligo treatment protocol likely slowed the response rate for those patients with vitiligo, the numbers were small (ie, only 3 of 52 patients), so the researchers chose to include them in the current study. The sample population was relatively small, but when these data are evaluated alongside the studies in the United Kingdom¹⁶ and Turkey,¹⁷ they show a consistent picture illustrating the effectiveness and safety of phototherapy in the older population. Further epidemiologic studies could be helpful to further describe the usefulness of this modality compared with other treatments for a variety of dermatoses in this age group. Supplementary analysis specifically examining the relationship between the number and type of photosensitizing medications, frequency of erythema, and time to clearance also could be useful.

Conclusion

Older adults with a variety of dermatoses respond well to phototherapy and should have the opportunity to use it, particularly considering the potential for increased complications and costs from other treatment modalities, such as commonly used immunosuppressive pharmaceuticals. However, the current study and the comparison studies indicate that it is important to carefully consider the slower clearance rates and the potential risk for increased erythema in this population and adjust patient education and treatment dosing accordingly.

Unfortunately, many dermatology centers do not offer phototherapy because of infrastructure limitations such as space and specially trained nursing staff. Increasing accessibility of phototherapy for older adults through home treatments may be an alternative, given its effectiveness in the general population.^22,23 In addition, home phototherapy may be worth pursuing for the older population considering the challenges they may face with transportation to the clinic setting and their increased risk for serious illness if exposed to infections such as COVID-19. The COVID-19 pandemic has brought to light the need for reliable, safe, and effective treatments that can be utilized in the safety of patients’ homes and should therefore be considered as an option for older adults. Issues such as mobility and cognitive decline could pose some complicating factors, but with the help of a well-trained family member or caregiver, home phototherapy could be a viable option that improves accessibility for older patients. Future research opportunities include further examination of the slower but ultimately equivalent response to phototherapy in the older population, the influence of photosensitizing medications on phototherapy effects, and the impact of phototherapy on utilization of immunosuppressive pharmaceuticals in older adults.

Identifying safe, effective, and affordable evidence-based dermatologic treatments for older adults can be challenging because of age-related changes in the skin, comorbidities, polypharmacy, mobility issues, and cognitive changes. Phototherapy has been shown to be an effective nonpharmacologic treatment option for multiple challenging dermatologic conditions^1-8; however, few studies have specifically examined its effectiveness in older adults. The challenge for older patients with psoriasis and dermatitis is that the conditions can be difficult to control and often require multiple treatment modalities.^9,10 Patients with psoriasis also have a higher risk for diabetes, dyslipidemia, and cardiovascular disease compared to other older patients,^11,12 which poses treatment challenges and makes nonpharmacologic treatments even more appealing.

Recent studies show that phototherapy can help decrease the use of dermatologic medications. Foerster and colleagues² found that adults with psoriasis who were treated with phototherapy significantly decreased their use of topical steroids (24.5% fewer patients required steroid creams and 31.1% fewer patients required psoriasis-specific topicals)(P<.01) while their use of non–psoriasis-specific medications did not change. Click and colleagues¹³ identified a decrease in medication costs, health care utilization, and risk for immunosuppression in patients treated with phototherapy when compared to those treated with biologics and apremilast. Methotrexate is a common dermatologic medication that is highly associated with increased risks in elderly patients because of impaired immune system function and the presence of comorbidities (eg, kidney disease, obesity, diabetes, fatty liver),¹⁴ which increase in prevalence with age. Combining phototherapy with methotrexate can substantially decrease the amount of methotrexate needed to achieve disease control,¹⁵ thereby decreasing the methotrexate-associated risks. Findings from these studies suggest that a safe, effective, cost-effective, and well-tolerated nonpharmacologic alternative, such as phototherapy, is highly desirable and should be optimized. Unfortunately, most studies that report the effectiveness of phototherapy are in younger populations.

This retrospective study aimed to (1) identify the most common dermatologic conditions treated with phototherapy in older adults, (2) examine the effectiveness and safety of phototherapy in older adults, and (3) compare the outcomes with 2 similar studies in the United Kingdom¹⁶ and Turkey.¹⁷

Methods

Design, Setting, Sample, and Statistical Analysis
The institutional review boards of Kaiser Permanente Washington Health Research Institute, Seattle, and the University of Washington, Seattle, approved this study. It was conducted in a large US multispecialty health care system (Group Health, Seattle, Washington [now Kaiser Permanente Washington]) serving approximately 600,000 patients, using billing records to identify all patients treated with phototherapy between January 1, 2015, and December 31, 2015, all who received narrowband UVB (NB-UVB) phototherapy. All adults 65 years and older who received phototherapy treatment during the 12-month study period were included. Patients were included regardless of comorbidities and other dermatologic treatments to maintain as much uniformity as possible between the present study and 2 prior studies examining phototherapy in older adult populations in the United Kingdom¹⁶ and Turkey.¹⁷ Demographic and clinical factors were presented using frequencies (percentages) or means and medians as appropriate. Comparisons of dermatologic conditions and clearance levels used a Fisher exact test. The number of phototherapy treatments to clearance and total number of treatments were compared between groups of patients using independent sample t tests.

Phototherapy Protocol
All patients received treatments administered by specially trained phototherapy nurses using a Daavlin UV Series (The Daavlin Company) or an Ultralite unit (Ultralite Enterprises, Inc), both with 48 lamps. All phototherapy nurses had been previously trained to provide treatments based on standardized protocols (Table 1) and to determine the patient’s level of disease clearance using a high to low clearance scale (Table 2). Daavlin’s treatment protocols were built into the software that accompanied the units and were developed based on the American Academy of Dermatology guidelines. The starting dose for an individual patient was determined based on the estimated minimal erythema dose for each phototype. If the patient was using photosensitizing medications, then the protocol guided the nurse to start the patient at a lower dose appropriate for their phototype. Patients with vitiligo were treated with the same starting and escalation doses as patients with Fitzpatrick phototype I because of the assumption that their vitiliginous skin had an increased risk for photosensitivity. A more recent review of the evidence has indicated that this assumption was overly conservative,¹⁸ and Kaiser Permanente Washington’s vitiligo protocol has been adjusted.

Results

Patients
Billing records identified 229 total patients who received phototherapy in 2015, of whom 52 (22.7%) were at least 65 years old. The median age was 70 years (range, 65–91 years). Twenty-nine (56%) were men and 35 (67%) had previously received phototherapy treatments.

Dermatologic Conditions Treated With Phototherapy
Our primary aim was to identify the most common dermatologic conditions treated with phototherapy in older adults. Psoriasis and dermatitis were the most common conditions treated in the sample (50% [26/52] and 21% [11/52], respectively), with mycosis fungoides being the third most common (10% [5/52]) and vitiligo tied with prurigo nodularis as fourth most common (6% [3/52])(Figure 1).

Effectiveness and Safety of Phototherapy
Our secondary aim was to examine the effectiveness and safety of phototherapy in older adults. Phototherapy was effective in this population, with 50 of 52 patients (96%) achieving a high or medium level of clearance. The degree of clearance for each of the dermatologic conditions is shown in Figure 2. Psoriasis and dermatitis achieved high clearance rates in 81% (21/26) and 82% (9/11) of patients, respectively. Overall, conditions did not have significant differences in clearances rates (Fisher exact test, P=.10). On average, it took patients 33 treatments to achieve medium or high rates of clearance. Psoriasis cleared more quickly, with an average of 30.4 treatments vs 36.1 treatments for other conditions, but the difference was not significant (t test, P=.26). Patients received an average of 98 total phototherapy treatments; the median number of treatments was 81 due to many being on maintenance therapy over several months. There was no relationship between a history of treatment with phototherapy and the total number of treatments needed to achieve clearance (t test, P=.40), but interestingly, those who had a history of phototherapy took approximately 5 more treatments to achieve clearance. The present study found that a slightly larger number of men were being treated for psoriasis (15 men vs 11 women), but there was no significant difference in response rate based on gender.

Comment

Our study found that 94% of patients with psoriasis achieved clearance with an average of 30.4 treatments, which is comparable to the reported 91% response rate with an average of 30 treatments in the United Kingdom.¹⁶ The other similar study in Turkey¹⁷ reported 73.7% of psoriasis patients achieved a 75% or more improvement from baseline with an average of 42 treatments, which may reflect underlying differences in regional skin type. Of note, the scatter chart (Figure 3) shows that several patients in the present study’s analysis are listed as not clear, but many of those patients had low treatment numbers below the mean time to clearance. Thus, the present study’s response rate may have been underestimated.

In the general population, studies show that psoriasis treated with standardized phototherapy protocols typically clears with an average of 20.6 treatments.²¹ The levels of clearance were similar in our study’s older population, but more treatments were required to achieve those results, with an average of 10 more treatments needed (an additional 3.3 weeks). Similar results were found in this sample for dermatitis and mycosis fungoides, indicating comparable clearance rates and levels but a need for more treatments to achieve similar results compared to the general population.

Additionally, in the current study more patients experienced grade 1 (mild) erythema (46%) and grade 2 erythema (25%) at some point in their treatment compared with the United Kingdom¹⁶ (1.89%) and Turkey¹⁷ (35%) studies, though these side effects did not impact the clearance rate. Interestingly, the current study’s scatter chart (Figure 3) illustrates that this side effect did not seem to increase with aging in this population. If anything, the erythema response was more prevalent in the median or younger patients in the sample. Erythema may have been due to the frequent use of photosensitizing medications in older adults in the United States, some of which typically get discontinued in patients 75 years and older (eg, statins). Other potential causes might include the use of phototype vs minimal erythema dose–driven protocols, the standard utilization of protocols originally designed for psoriasis vs other condition-specific protocols, missed treatments leading to increased sensitivity, or possibly shielding mishaps (eg, not wearing a prescribed face shield). Given the number of potential causes and the possibility of overlapping factors, careful analysis is important. With NB-UVB phototherapy, near-erythemogenic doses are optimal to achieve effective treatments, but this delicate balance may be more problematic for older adults. Future studies are needed to fully determine the factors at play for this population. In the interim, it is important for phototherapy-trained nurses to consider this risk carefully in the older population. They must follow the prescribed protocols that guide them to query patients about their responses to the prior treatment (eg, erythema, tenderness, itching), photosensitizing medications, missed treatments, and placement of shielding, and then adjust the treatment dosing accordingly.

Limitations
This study had several limitations. Although clinical outcomes were recorded prospectively, the analysis was retrospective, unblinded, and not placebo controlled. It was conducted in a single organization (Group Health [now Kaiser Permanente Washington]) but did analyze data from 4 medical centers in different cities with diverse demographics and a variety of nursing staff providing the treatments. Although the vitiligo treatment protocol likely slowed the response rate for those patients with vitiligo, the numbers were small (ie, only 3 of 52 patients), so the researchers chose to include them in the current study. The sample population was relatively small, but when these data are evaluated alongside the studies in the United Kingdom¹⁶ and Turkey,¹⁷ they show a consistent picture illustrating the effectiveness and safety of phototherapy in the older population. Further epidemiologic studies could be helpful to further describe the usefulness of this modality compared with other treatments for a variety of dermatoses in this age group. Supplementary analysis specifically examining the relationship between the number and type of photosensitizing medications, frequency of erythema, and time to clearance also could be useful.

Conclusion

Older adults with a variety of dermatoses respond well to phototherapy and should have the opportunity to use it, particularly considering the potential for increased complications and costs from other treatment modalities, such as commonly used immunosuppressive pharmaceuticals. However, the current study and the comparison studies indicate that it is important to carefully consider the slower clearance rates and the potential risk for increased erythema in this population and adjust patient education and treatment dosing accordingly.

Unfortunately, many dermatology centers do not offer phototherapy because of infrastructure limitations such as space and specially trained nursing staff. Increasing accessibility of phototherapy for older adults through home treatments may be an alternative, given its effectiveness in the general population.^22,23 In addition, home phototherapy may be worth pursuing for the older population considering the challenges they may face with transportation to the clinic setting and their increased risk for serious illness if exposed to infections such as COVID-19. The COVID-19 pandemic has brought to light the need for reliable, safe, and effective treatments that can be utilized in the safety of patients’ homes and should therefore be considered as an option for older adults. Issues such as mobility and cognitive decline could pose some complicating factors, but with the help of a well-trained family member or caregiver, home phototherapy could be a viable option that improves accessibility for older patients. Future research opportunities include further examination of the slower but ultimately equivalent response to phototherapy in the older population, the influence of photosensitizing medications on phototherapy effects, and the impact of phototherapy on utilization of immunosuppressive pharmaceuticals in older adults.

The increased use of masks caused by the COVID-19 pandemic was accompanied by a “dramatic increase in face mask–related injuries” reported to a national surveillance system.

How dramatic? The number of mask-related injuries treated in U.S. emergency departments averaged about 200 per year from 2016 to 2019. In 2020, that figure soared to 4,976 – an increase of almost 2,400%, Gerald McGwin Jr., PhD, and associates said in a research letter published in the Journal to the American Academy of Dermatology.

“Prior to the COVID-19 pandemic the use of respiratory protection equipment was largely limited to healthcare and industrial settings. As [face mask] use by the general population increased, so too have reports of dermatologic reactions,” said Dr. McGwin and associates of the department of epidemiology at the University of Alabama at Birmingham.

Dermatitis was the most common mask-related injury treated last year, affecting 28.3% of those presenting to EDs, followed by lacerations at 10.1%. Injuries were more common in women than men, but while and black patients “were equally represented,” they noted, based on data from the National Electronic Injury Surveillance System, which includes about 100 hospitals and EDs.

Most injuries were caused by rashes/allergic reactions (38%) from prolonged use, poorly fitting masks (19%), and obscured vision (14%). “There was a small (5%) but meaningful number of injuries, all among children, attributable to consuming pieces of a mask or inserting dismantled pieces of a mask into body orifices,” the investigators said.

Guidance from the Centers for Disease Control and Prevention is available “to aid in the choice and proper fit of face masks,” they wrote, and “increased awareness of these resources [could] minimize the future occurrence of mask-related injuries.”

There was no funding source for the study, and the investigators did not declare any conflicts of interest.

[email protected]

The increased use of masks caused by the COVID-19 pandemic was accompanied by a “dramatic increase in face mask–related injuries” reported to a national surveillance system.

How dramatic? The number of mask-related injuries treated in U.S. emergency departments averaged about 200 per year from 2016 to 2019. In 2020, that figure soared to 4,976 – an increase of almost 2,400%, Gerald McGwin Jr., PhD, and associates said in a research letter published in the Journal to the American Academy of Dermatology.

“Prior to the COVID-19 pandemic the use of respiratory protection equipment was largely limited to healthcare and industrial settings. As [face mask] use by the general population increased, so too have reports of dermatologic reactions,” said Dr. McGwin and associates of the department of epidemiology at the University of Alabama at Birmingham.

Dermatitis was the most common mask-related injury treated last year, affecting 28.3% of those presenting to EDs, followed by lacerations at 10.1%. Injuries were more common in women than men, but while and black patients “were equally represented,” they noted, based on data from the National Electronic Injury Surveillance System, which includes about 100 hospitals and EDs.

Most injuries were caused by rashes/allergic reactions (38%) from prolonged use, poorly fitting masks (19%), and obscured vision (14%). “There was a small (5%) but meaningful number of injuries, all among children, attributable to consuming pieces of a mask or inserting dismantled pieces of a mask into body orifices,” the investigators said.

Guidance from the Centers for Disease Control and Prevention is available “to aid in the choice and proper fit of face masks,” they wrote, and “increased awareness of these resources [could] minimize the future occurrence of mask-related injuries.”

There was no funding source for the study, and the investigators did not declare any conflicts of interest.

[email protected]

The increased use of masks caused by the COVID-19 pandemic was accompanied by a “dramatic increase in face mask–related injuries” reported to a national surveillance system.

How dramatic? The number of mask-related injuries treated in U.S. emergency departments averaged about 200 per year from 2016 to 2019. In 2020, that figure soared to 4,976 – an increase of almost 2,400%, Gerald McGwin Jr., PhD, and associates said in a research letter published in the Journal to the American Academy of Dermatology.

“Prior to the COVID-19 pandemic the use of respiratory protection equipment was largely limited to healthcare and industrial settings. As [face mask] use by the general population increased, so too have reports of dermatologic reactions,” said Dr. McGwin and associates of the department of epidemiology at the University of Alabama at Birmingham.

Dermatitis was the most common mask-related injury treated last year, affecting 28.3% of those presenting to EDs, followed by lacerations at 10.1%. Injuries were more common in women than men, but while and black patients “were equally represented,” they noted, based on data from the National Electronic Injury Surveillance System, which includes about 100 hospitals and EDs.

Most injuries were caused by rashes/allergic reactions (38%) from prolonged use, poorly fitting masks (19%), and obscured vision (14%). “There was a small (5%) but meaningful number of injuries, all among children, attributable to consuming pieces of a mask or inserting dismantled pieces of a mask into body orifices,” the investigators said.

Guidance from the Centers for Disease Control and Prevention is available “to aid in the choice and proper fit of face masks,” they wrote, and “increased awareness of these resources [could] minimize the future occurrence of mask-related injuries.”

There was no funding source for the study, and the investigators did not declare any conflicts of interest.

[email protected]

The world is an increasingly diverse place, which has particular relevance for the dermatologist. Skin color plays a significant role in diagnostic approach, as there are important differences in how cutaneous disease presents in patients with skin of color (SOC). Therefore, education about these differences is imperative. In this review, we focus on allergic contact dermatitis (ACD) and patch testing in patients with SOC. We discuss allergens common to this demographic and challenges encountered in patch testing patients with SOC. We also identify key health care disparities in the evaluation and management of ACD in this population.

Has contact allergy in SOC populations been studied in North America?

Over the last 2 decades, there have been only a handful of North American studies that address contact allergy in SOC populations. Patch test results from 114 Black patients and 877 White patients at the Cleveland Clinic from 1988 to 1991 showed that overall allergy frequency was relatively similar (43.0% vs 43.6%). There were notable differences in allergen sensitization. Paraphenylenediamine (PPD), which is used in hair dye, had more positive patch test reactions in Black patients (10.6% vs 4.5%), and both PPD (21.2% vs 4.2%) and imidazolidinyl urea, a formaldehyde-releasing preservative (9.1% vs 2.6%), were more frequently allergenic in Black men compared to White men.¹ Patch test results from the North American Contact Dermatitis Group from 1992 to 1998 described similar results, with minimal variation in the prevalence of ACD among 1014 Black and 8610 White patients (47%–49% vs 46%–49%).² Positive patch test reactions to PPD were higher in Black patients for 2 of 3 test cycles (13.5% vs 5.8% [1994-1996] and 10.3% vs 5.3% [1996-1998]). Positive patch test reactions were higher in White patients for dimethylol dimethyl hydantoin, a formaldehyde-releasing preservative, also for 2 of 3 test cycles (1.8% vs 0% [1992-1994] and 2.8% vs 0.3% [1994-1996]). Finally, positive patch test reactions to thioureas (rubber accelerators) had a mixed picture: 2 test cycles were higher in Black patients (1.9% vs 1.0% [1992-1994] and 1.3% vs 0.7% [1994-1996]), but the third cycle (1996-1998) was lower (0.7% vs 1.4%). Positive patch test reactions to the metal cobalt chloride were higher in Black patients in just 1 test cycle (9.2% vs 6.6% [1992-1994]). The authors suggested that the use of darker hair dyes in the Black community may lead to more sensitization to PPD. They also theorized that this population’s more frequent use of ointment-based skin care products may make them less susceptible to sensitization to preservatives such as formaldehyde, which more commonly are found in water-based products such as creams. They concluded that differences in sensitization patterns likely were driven by cultural practices affecting exposures.²

In 2016, the North American Contact Dermatitis Group reported patch test results in 434 Black and 6634 White patients (1998-2006).³ Again, ACD prevalence was about the same in both groups (45.9% vs 43.6%). However, they reported several allergens with different reaction patterns. Black patients had higher risk ratios (RRs) for 3 rubber accelerators: mercaptobenzothiazole (RR, 2.10), mercapto mix (RR, 2.27), and thiuram mix (RR, 1.44). They also reacted to PPD (RR, 1.56) and the antibiotic bacitracin (RR, 1.34) at higher frequencies than White patients, who more frequently reacted to formaldehyde (RR, 0.58); the formaldehyde-releasing preservatives quaternium-15 (RR, 0.63) and diazolidinyl urea (in petrolatum: RR, 0.44; aqueous: RR, 0.47); the clothing finish ethylene urea melamine formalin resin (RR, 0.45); and the fragrances fragrance mix 1 (RR, 0.65) and balsam of Peru (RR, 0.55).³

Patch testing of 139 African American or Black patients at the Cleveland Clinic (2003-2012) revealed that this population most commonly had positive reactions to nickel (27.5%), fragrance mix (18.1%), bacitracin (13.0%), balsam of Peru (12.3%), and PPD (10.9%). The authors highlighted unique features of physical examination in patients with darker skin types, including lichenification and/or hyperpigmentation in those with ACD and the potential for lack of erythema and/or a papular reaction with patch test readings.⁴ Recently, data was presented at the American Contact Dermatitis Society Annual Meeting (March 2021) on patterns of ACD in Black and White patch tested patients in Philadelphia (2009-2019).⁵ Using the North American 80 comprehensive series, the researchers documented statistically significant differences in allergen sensitivity between the 2 groups. Black patients reacted to disperse blue dye (P=.019) and textile dye mix (P=.001) at higher frequencies. There was a nonsignificant trend of more frequent positive reactions to PPD in Black patients (11% vs 6%).⁵

Notably, all of these studies examined only 1 or 2 racial groups with a focus on Black patients. Some authors commented that this was due to low numbers of Hispanic, Asian and Pacific Islander, and Native American patients in tested populations.^2,3,5 With approximately 13% of the US population self-identifying as Black,⁶ these patients and other minority races typically are underrepresented in large patch test studies. More data on patch test results for these groups is necessary for a complete understanding of patch testing in patients with SOC.

What are the challenges in patch testing SOC populations?

Patch testing in patients with SOC requires additional skills and experience. Darker skin does not reveal erythema as strikingly as lighter skin, making it more difficult to appreciate subtle color changes. Moreover, multiple studies have shown that ACD can have different presentations in Black patients.^4,7,8 Lichenification and hyperpigmentation may be early signs of ACD in comparison to bright erythema and vesicles that can be seen in lighter skin types. It also has been reported that scalp ACD can be mistaken for seborrheic dermatitis due to lack of erythema.⁷ Without a high degree of clinical suspicion, a diagnosis of ACD can be missed in this patient population.

Patch test interpretation also can be challenging in patients with SOC. An early papular or follicular eruption with minimal erythema can signal a positive reaction.^4,7 Because of these potentially subtle changes, patch testers should exercise care and attention when reading results for SOC populations. We recommend ample side lighting, palpation for adequate identification of positive reactions, and double-checking for positives that may have been overlooked on the initial review of findings.^4,7

What health care disparities impact the evaluation and management of ACD?

There are many factors at play in this dialogue. The challenges we identified in diagnosing ACD in darker skin types are important to consider. Lack of familiarity with these unique features can lead to a delay in diagnosis and ultimately a delay in referral for patch testing. This is where dermatology training can help fill in the gap, but are the majority of programs equipped to do so? Inadequate education and exposure to patients with SOC is an issue for many dermatology residency programs. Surveys of residents and program directors in geographically less diverse regions may not receive adequate education or exposure to patients with SOC.⁹ Further, there is a lack of representation of SOC images for general dermatologic conditions in textbooks,^10,11 which has a profound impact on the dermatologist’s ability to recognize common diseases in darker skin types. A 2019 survey of more than 5000 images from 2 dermatology textbooks showed SOC images comprised 22% to 32% of the total images.¹¹ However, SOC images are overrepresented in textbooks for sexually transmitted infections, constituting 47% to 58% of the images; they made up 28% of images for nonvenereal infections.¹¹ Why is that? In this article, we have shown the prevalence of ACD to be nearly equivalent in Black and White patients, yet a perusal of ACD images in dermatology textbooks will tell a different story. This trend deserves our attention; perhaps it is highlighting patterns of systemic racism seen in medicine. If our primary teaching materials are perpetuating stereotypes, we must consider the impact this can have on our personal implicit biases and the health care disparities that can ensue.

Additional factors impact time to diagnosis of ACD and referral for patch testing. A retrospective study examining distance to a North Carolina patch test referral clinic showed that patients living further from the clinic experienced a longer duration of dermatitis prior to patch test consultation and tended to live in areas with a higher county poverty rate.¹² Specifically, a 17.9% increase (P<.001) in the median duration of dermatitis was observed for every 50-mile increase in distance to the patch test clinic. County poverty rate was measured by the percentage of residents living below the poverty threshold; for every 5% increase in county poverty rate, a 16.3% increase (P<.032) in duration of dermatitis was found.¹²

These data highlight a relationship with which many dermatologists are familiar and underscore a need for dermatologists to practice in areas that are more geographically accessible. The recently increased utilization of telehealth modalities can potentially help to bridge this gap by decreasing delays in diagnosis and providing more affordable options for evaluation by a dermatologist for patients with socioeconomic obstacles.

Final Interpretation

The prevalence of ACD among Black and White patients is similar; however, there are important differences in patch test reaction frequencies that may be related to the diverse exposure patterns for each group. Additionally, patients with SOC may have unique clinical presentations of ACD, such as lichenification and hyperpigmentation. Darker skin types also may require specialized techniques for accurate patch test readings. It is imperative that dermatologists are trained to recognize all of these features. Health care disparities come in many forms and, in this setting, can result in delayed referral for patch testing. Additional studies are needed to further examine these health care disparities and identify potential solutions.

The world is an increasingly diverse place, which has particular relevance for the dermatologist. Skin color plays a significant role in diagnostic approach, as there are important differences in how cutaneous disease presents in patients with skin of color (SOC). Therefore, education about these differences is imperative. In this review, we focus on allergic contact dermatitis (ACD) and patch testing in patients with SOC. We discuss allergens common to this demographic and challenges encountered in patch testing patients with SOC. We also identify key health care disparities in the evaluation and management of ACD in this population.

Has contact allergy in SOC populations been studied in North America?

Over the last 2 decades, there have been only a handful of North American studies that address contact allergy in SOC populations. Patch test results from 114 Black patients and 877 White patients at the Cleveland Clinic from 1988 to 1991 showed that overall allergy frequency was relatively similar (43.0% vs 43.6%). There were notable differences in allergen sensitization. Paraphenylenediamine (PPD), which is used in hair dye, had more positive patch test reactions in Black patients (10.6% vs 4.5%), and both PPD (21.2% vs 4.2%) and imidazolidinyl urea, a formaldehyde-releasing preservative (9.1% vs 2.6%), were more frequently allergenic in Black men compared to White men.¹ Patch test results from the North American Contact Dermatitis Group from 1992 to 1998 described similar results, with minimal variation in the prevalence of ACD among 1014 Black and 8610 White patients (47%–49% vs 46%–49%).² Positive patch test reactions to PPD were higher in Black patients for 2 of 3 test cycles (13.5% vs 5.8% [1994-1996] and 10.3% vs 5.3% [1996-1998]). Positive patch test reactions were higher in White patients for dimethylol dimethyl hydantoin, a formaldehyde-releasing preservative, also for 2 of 3 test cycles (1.8% vs 0% [1992-1994] and 2.8% vs 0.3% [1994-1996]). Finally, positive patch test reactions to thioureas (rubber accelerators) had a mixed picture: 2 test cycles were higher in Black patients (1.9% vs 1.0% [1992-1994] and 1.3% vs 0.7% [1994-1996]), but the third cycle (1996-1998) was lower (0.7% vs 1.4%). Positive patch test reactions to the metal cobalt chloride were higher in Black patients in just 1 test cycle (9.2% vs 6.6% [1992-1994]). The authors suggested that the use of darker hair dyes in the Black community may lead to more sensitization to PPD. They also theorized that this population’s more frequent use of ointment-based skin care products may make them less susceptible to sensitization to preservatives such as formaldehyde, which more commonly are found in water-based products such as creams. They concluded that differences in sensitization patterns likely were driven by cultural practices affecting exposures.²

In 2016, the North American Contact Dermatitis Group reported patch test results in 434 Black and 6634 White patients (1998-2006).³ Again, ACD prevalence was about the same in both groups (45.9% vs 43.6%). However, they reported several allergens with different reaction patterns. Black patients had higher risk ratios (RRs) for 3 rubber accelerators: mercaptobenzothiazole (RR, 2.10), mercapto mix (RR, 2.27), and thiuram mix (RR, 1.44). They also reacted to PPD (RR, 1.56) and the antibiotic bacitracin (RR, 1.34) at higher frequencies than White patients, who more frequently reacted to formaldehyde (RR, 0.58); the formaldehyde-releasing preservatives quaternium-15 (RR, 0.63) and diazolidinyl urea (in petrolatum: RR, 0.44; aqueous: RR, 0.47); the clothing finish ethylene urea melamine formalin resin (RR, 0.45); and the fragrances fragrance mix 1 (RR, 0.65) and balsam of Peru (RR, 0.55).³

Patch testing of 139 African American or Black patients at the Cleveland Clinic (2003-2012) revealed that this population most commonly had positive reactions to nickel (27.5%), fragrance mix (18.1%), bacitracin (13.0%), balsam of Peru (12.3%), and PPD (10.9%). The authors highlighted unique features of physical examination in patients with darker skin types, including lichenification and/or hyperpigmentation in those with ACD and the potential for lack of erythema and/or a papular reaction with patch test readings.⁴ Recently, data was presented at the American Contact Dermatitis Society Annual Meeting (March 2021) on patterns of ACD in Black and White patch tested patients in Philadelphia (2009-2019).⁵ Using the North American 80 comprehensive series, the researchers documented statistically significant differences in allergen sensitivity between the 2 groups. Black patients reacted to disperse blue dye (P=.019) and textile dye mix (P=.001) at higher frequencies. There was a nonsignificant trend of more frequent positive reactions to PPD in Black patients (11% vs 6%).⁵

Notably, all of these studies examined only 1 or 2 racial groups with a focus on Black patients. Some authors commented that this was due to low numbers of Hispanic, Asian and Pacific Islander, and Native American patients in tested populations.^2,3,5 With approximately 13% of the US population self-identifying as Black,⁶ these patients and other minority races typically are underrepresented in large patch test studies. More data on patch test results for these groups is necessary for a complete understanding of patch testing in patients with SOC.

What are the challenges in patch testing SOC populations?

Patch testing in patients with SOC requires additional skills and experience. Darker skin does not reveal erythema as strikingly as lighter skin, making it more difficult to appreciate subtle color changes. Moreover, multiple studies have shown that ACD can have different presentations in Black patients.^4,7,8 Lichenification and hyperpigmentation may be early signs of ACD in comparison to bright erythema and vesicles that can be seen in lighter skin types. It also has been reported that scalp ACD can be mistaken for seborrheic dermatitis due to lack of erythema.⁷ Without a high degree of clinical suspicion, a diagnosis of ACD can be missed in this patient population.

Patch test interpretation also can be challenging in patients with SOC. An early papular or follicular eruption with minimal erythema can signal a positive reaction.^4,7 Because of these potentially subtle changes, patch testers should exercise care and attention when reading results for SOC populations. We recommend ample side lighting, palpation for adequate identification of positive reactions, and double-checking for positives that may have been overlooked on the initial review of findings.^4,7

What health care disparities impact the evaluation and management of ACD?

There are many factors at play in this dialogue. The challenges we identified in diagnosing ACD in darker skin types are important to consider. Lack of familiarity with these unique features can lead to a delay in diagnosis and ultimately a delay in referral for patch testing. This is where dermatology training can help fill in the gap, but are the majority of programs equipped to do so? Inadequate education and exposure to patients with SOC is an issue for many dermatology residency programs. Surveys of residents and program directors in geographically less diverse regions may not receive adequate education or exposure to patients with SOC.⁹ Further, there is a lack of representation of SOC images for general dermatologic conditions in textbooks,^10,11 which has a profound impact on the dermatologist’s ability to recognize common diseases in darker skin types. A 2019 survey of more than 5000 images from 2 dermatology textbooks showed SOC images comprised 22% to 32% of the total images.¹¹ However, SOC images are overrepresented in textbooks for sexually transmitted infections, constituting 47% to 58% of the images; they made up 28% of images for nonvenereal infections.¹¹ Why is that? In this article, we have shown the prevalence of ACD to be nearly equivalent in Black and White patients, yet a perusal of ACD images in dermatology textbooks will tell a different story. This trend deserves our attention; perhaps it is highlighting patterns of systemic racism seen in medicine. If our primary teaching materials are perpetuating stereotypes, we must consider the impact this can have on our personal implicit biases and the health care disparities that can ensue.

Additional factors impact time to diagnosis of ACD and referral for patch testing. A retrospective study examining distance to a North Carolina patch test referral clinic showed that patients living further from the clinic experienced a longer duration of dermatitis prior to patch test consultation and tended to live in areas with a higher county poverty rate.¹² Specifically, a 17.9% increase (P<.001) in the median duration of dermatitis was observed for every 50-mile increase in distance to the patch test clinic. County poverty rate was measured by the percentage of residents living below the poverty threshold; for every 5% increase in county poverty rate, a 16.3% increase (P<.032) in duration of dermatitis was found.¹²

These data highlight a relationship with which many dermatologists are familiar and underscore a need for dermatologists to practice in areas that are more geographically accessible. The recently increased utilization of telehealth modalities can potentially help to bridge this gap by decreasing delays in diagnosis and providing more affordable options for evaluation by a dermatologist for patients with socioeconomic obstacles.

Final Interpretation

The prevalence of ACD among Black and White patients is similar; however, there are important differences in patch test reaction frequencies that may be related to the diverse exposure patterns for each group. Additionally, patients with SOC may have unique clinical presentations of ACD, such as lichenification and hyperpigmentation. Darker skin types also may require specialized techniques for accurate patch test readings. It is imperative that dermatologists are trained to recognize all of these features. Health care disparities come in many forms and, in this setting, can result in delayed referral for patch testing. Additional studies are needed to further examine these health care disparities and identify potential solutions.

The world is an increasingly diverse place, which has particular relevance for the dermatologist. Skin color plays a significant role in diagnostic approach, as there are important differences in how cutaneous disease presents in patients with skin of color (SOC). Therefore, education about these differences is imperative. In this review, we focus on allergic contact dermatitis (ACD) and patch testing in patients with SOC. We discuss allergens common to this demographic and challenges encountered in patch testing patients with SOC. We also identify key health care disparities in the evaluation and management of ACD in this population.

Has contact allergy in SOC populations been studied in North America?

Over the last 2 decades, there have been only a handful of North American studies that address contact allergy in SOC populations. Patch test results from 114 Black patients and 877 White patients at the Cleveland Clinic from 1988 to 1991 showed that overall allergy frequency was relatively similar (43.0% vs 43.6%). There were notable differences in allergen sensitization. Paraphenylenediamine (PPD), which is used in hair dye, had more positive patch test reactions in Black patients (10.6% vs 4.5%), and both PPD (21.2% vs 4.2%) and imidazolidinyl urea, a formaldehyde-releasing preservative (9.1% vs 2.6%), were more frequently allergenic in Black men compared to White men.¹ Patch test results from the North American Contact Dermatitis Group from 1992 to 1998 described similar results, with minimal variation in the prevalence of ACD among 1014 Black and 8610 White patients (47%–49% vs 46%–49%).² Positive patch test reactions to PPD were higher in Black patients for 2 of 3 test cycles (13.5% vs 5.8% [1994-1996] and 10.3% vs 5.3% [1996-1998]). Positive patch test reactions were higher in White patients for dimethylol dimethyl hydantoin, a formaldehyde-releasing preservative, also for 2 of 3 test cycles (1.8% vs 0% [1992-1994] and 2.8% vs 0.3% [1994-1996]). Finally, positive patch test reactions to thioureas (rubber accelerators) had a mixed picture: 2 test cycles were higher in Black patients (1.9% vs 1.0% [1992-1994] and 1.3% vs 0.7% [1994-1996]), but the third cycle (1996-1998) was lower (0.7% vs 1.4%). Positive patch test reactions to the metal cobalt chloride were higher in Black patients in just 1 test cycle (9.2% vs 6.6% [1992-1994]). The authors suggested that the use of darker hair dyes in the Black community may lead to more sensitization to PPD. They also theorized that this population’s more frequent use of ointment-based skin care products may make them less susceptible to sensitization to preservatives such as formaldehyde, which more commonly are found in water-based products such as creams. They concluded that differences in sensitization patterns likely were driven by cultural practices affecting exposures.²

In 2016, the North American Contact Dermatitis Group reported patch test results in 434 Black and 6634 White patients (1998-2006).³ Again, ACD prevalence was about the same in both groups (45.9% vs 43.6%). However, they reported several allergens with different reaction patterns. Black patients had higher risk ratios (RRs) for 3 rubber accelerators: mercaptobenzothiazole (RR, 2.10), mercapto mix (RR, 2.27), and thiuram mix (RR, 1.44). They also reacted to PPD (RR, 1.56) and the antibiotic bacitracin (RR, 1.34) at higher frequencies than White patients, who more frequently reacted to formaldehyde (RR, 0.58); the formaldehyde-releasing preservatives quaternium-15 (RR, 0.63) and diazolidinyl urea (in petrolatum: RR, 0.44; aqueous: RR, 0.47); the clothing finish ethylene urea melamine formalin resin (RR, 0.45); and the fragrances fragrance mix 1 (RR, 0.65) and balsam of Peru (RR, 0.55).³

Patch testing of 139 African American or Black patients at the Cleveland Clinic (2003-2012) revealed that this population most commonly had positive reactions to nickel (27.5%), fragrance mix (18.1%), bacitracin (13.0%), balsam of Peru (12.3%), and PPD (10.9%). The authors highlighted unique features of physical examination in patients with darker skin types, including lichenification and/or hyperpigmentation in those with ACD and the potential for lack of erythema and/or a papular reaction with patch test readings.⁴ Recently, data was presented at the American Contact Dermatitis Society Annual Meeting (March 2021) on patterns of ACD in Black and White patch tested patients in Philadelphia (2009-2019).⁵ Using the North American 80 comprehensive series, the researchers documented statistically significant differences in allergen sensitivity between the 2 groups. Black patients reacted to disperse blue dye (P=.019) and textile dye mix (P=.001) at higher frequencies. There was a nonsignificant trend of more frequent positive reactions to PPD in Black patients (11% vs 6%).⁵

Notably, all of these studies examined only 1 or 2 racial groups with a focus on Black patients. Some authors commented that this was due to low numbers of Hispanic, Asian and Pacific Islander, and Native American patients in tested populations.^2,3,5 With approximately 13% of the US population self-identifying as Black,⁶ these patients and other minority races typically are underrepresented in large patch test studies. More data on patch test results for these groups is necessary for a complete understanding of patch testing in patients with SOC.

What are the challenges in patch testing SOC populations?

Patch testing in patients with SOC requires additional skills and experience. Darker skin does not reveal erythema as strikingly as lighter skin, making it more difficult to appreciate subtle color changes. Moreover, multiple studies have shown that ACD can have different presentations in Black patients.^4,7,8 Lichenification and hyperpigmentation may be early signs of ACD in comparison to bright erythema and vesicles that can be seen in lighter skin types. It also has been reported that scalp ACD can be mistaken for seborrheic dermatitis due to lack of erythema.⁷ Without a high degree of clinical suspicion, a diagnosis of ACD can be missed in this patient population.

Patch test interpretation also can be challenging in patients with SOC. An early papular or follicular eruption with minimal erythema can signal a positive reaction.^4,7 Because of these potentially subtle changes, patch testers should exercise care and attention when reading results for SOC populations. We recommend ample side lighting, palpation for adequate identification of positive reactions, and double-checking for positives that may have been overlooked on the initial review of findings.^4,7

What health care disparities impact the evaluation and management of ACD?

There are many factors at play in this dialogue. The challenges we identified in diagnosing ACD in darker skin types are important to consider. Lack of familiarity with these unique features can lead to a delay in diagnosis and ultimately a delay in referral for patch testing. This is where dermatology training can help fill in the gap, but are the majority of programs equipped to do so? Inadequate education and exposure to patients with SOC is an issue for many dermatology residency programs. Surveys of residents and program directors in geographically less diverse regions may not receive adequate education or exposure to patients with SOC.⁹ Further, there is a lack of representation of SOC images for general dermatologic conditions in textbooks,^10,11 which has a profound impact on the dermatologist’s ability to recognize common diseases in darker skin types. A 2019 survey of more than 5000 images from 2 dermatology textbooks showed SOC images comprised 22% to 32% of the total images.¹¹ However, SOC images are overrepresented in textbooks for sexually transmitted infections, constituting 47% to 58% of the images; they made up 28% of images for nonvenereal infections.¹¹ Why is that? In this article, we have shown the prevalence of ACD to be nearly equivalent in Black and White patients, yet a perusal of ACD images in dermatology textbooks will tell a different story. This trend deserves our attention; perhaps it is highlighting patterns of systemic racism seen in medicine. If our primary teaching materials are perpetuating stereotypes, we must consider the impact this can have on our personal implicit biases and the health care disparities that can ensue.

Additional factors impact time to diagnosis of ACD and referral for patch testing. A retrospective study examining distance to a North Carolina patch test referral clinic showed that patients living further from the clinic experienced a longer duration of dermatitis prior to patch test consultation and tended to live in areas with a higher county poverty rate.¹² Specifically, a 17.9% increase (P<.001) in the median duration of dermatitis was observed for every 50-mile increase in distance to the patch test clinic. County poverty rate was measured by the percentage of residents living below the poverty threshold; for every 5% increase in county poverty rate, a 16.3% increase (P<.032) in duration of dermatitis was found.¹²

These data highlight a relationship with which many dermatologists are familiar and underscore a need for dermatologists to practice in areas that are more geographically accessible. The recently increased utilization of telehealth modalities can potentially help to bridge this gap by decreasing delays in diagnosis and providing more affordable options for evaluation by a dermatologist for patients with socioeconomic obstacles.

Final Interpretation

The prevalence of ACD among Black and White patients is similar; however, there are important differences in patch test reaction frequencies that may be related to the diverse exposure patterns for each group. Additionally, patients with SOC may have unique clinical presentations of ACD, such as lichenification and hyperpigmentation. Darker skin types also may require specialized techniques for accurate patch test readings. It is imperative that dermatologists are trained to recognize all of these features. Health care disparities come in many forms and, in this setting, can result in delayed referral for patch testing. Additional studies are needed to further examine these health care disparities and identify potential solutions.

To the Editor:

Patients with psychocutaneous disorders present unique challenges to physicians. We illustrate the critical role that dermoscopy may play to illuminate exogenous skin pathology.

A 50-year-old woman with a reported medical history of systemic lupus erythematosus, chronic pain, and nonhealing leg ulcers presented to the emergency department with severe pain of the left lower leg and redness that was concerning for cellulitis. She sought treatment at an outside hospital for cellulitis 2 weeks prior but left against medical advice. Symptomatic review revealed chest pain, shortness of breath, nausea, vomiting, and diarrhea. The primary team started her on intravenous clindamycin and vancomycin for the presumed infection and scheduled narcotic medications due to concerns of intractable pain in the left leg. The dermatology department was consulted after failure to improve with 1 week of systemic antibiotics.

Physical examination revealed a geometric, atrophic, purple plaque on the left anterior shin from a prior leg ulcer as well as a diffuse red-pink patch extending from the knee to the ankle. Notably, the cellulitis spared the left posterior calf resting against the sheet and had a sharp line of demarcation at the distal shin. The leg was cool to the touch while the patient was distractible. She later reported that the leg was extremely tender to palpation. Dermoscopy revealed linear red pigments within skin furrows that accentuated skin lines (Figure). These findings raised suspicions of an external manipulation. The skin was wiped with an alcohol pad that removed a shimmering pink substance consistent in appearance to a cosmetic product. The skin beneath the cellulitis appeared normal.

Dermoscopy is not a standard method to diagnose cellulitis of the skin; however, when patients present with an atypical response to appropriate care, the presumed diagnosis must be challenged. This patient had dramatized symptoms, false medical history, and numerous hospitalizations that were suspicious for factitious disorder.¹ Furthermore, the physical examination was inconsistent with the classic course of cellulitis. In this case, dermoscopy had advantages over biopsies because it was noninvasive, gave immediate feedback, and provided a macroscopic view of the morphology. Via dermoscopy, we had an objective lens to distinguish cellulitis from cosmetic product and to obtain the correct diagnosis.

To the Editor:

Patients with psychocutaneous disorders present unique challenges to physicians. We illustrate the critical role that dermoscopy may play to illuminate exogenous skin pathology.

A 50-year-old woman with a reported medical history of systemic lupus erythematosus, chronic pain, and nonhealing leg ulcers presented to the emergency department with severe pain of the left lower leg and redness that was concerning for cellulitis. She sought treatment at an outside hospital for cellulitis 2 weeks prior but left against medical advice. Symptomatic review revealed chest pain, shortness of breath, nausea, vomiting, and diarrhea. The primary team started her on intravenous clindamycin and vancomycin for the presumed infection and scheduled narcotic medications due to concerns of intractable pain in the left leg. The dermatology department was consulted after failure to improve with 1 week of systemic antibiotics.

Physical examination revealed a geometric, atrophic, purple plaque on the left anterior shin from a prior leg ulcer as well as a diffuse red-pink patch extending from the knee to the ankle. Notably, the cellulitis spared the left posterior calf resting against the sheet and had a sharp line of demarcation at the distal shin. The leg was cool to the touch while the patient was distractible. She later reported that the leg was extremely tender to palpation. Dermoscopy revealed linear red pigments within skin furrows that accentuated skin lines (Figure). These findings raised suspicions of an external manipulation. The skin was wiped with an alcohol pad that removed a shimmering pink substance consistent in appearance to a cosmetic product. The skin beneath the cellulitis appeared normal.

Dermoscopy is not a standard method to diagnose cellulitis of the skin; however, when patients present with an atypical response to appropriate care, the presumed diagnosis must be challenged. This patient had dramatized symptoms, false medical history, and numerous hospitalizations that were suspicious for factitious disorder.¹ Furthermore, the physical examination was inconsistent with the classic course of cellulitis. In this case, dermoscopy had advantages over biopsies because it was noninvasive, gave immediate feedback, and provided a macroscopic view of the morphology. Via dermoscopy, we had an objective lens to distinguish cellulitis from cosmetic product and to obtain the correct diagnosis.

To the Editor:

Patients with psychocutaneous disorders present unique challenges to physicians. We illustrate the critical role that dermoscopy may play to illuminate exogenous skin pathology.

A 50-year-old woman with a reported medical history of systemic lupus erythematosus, chronic pain, and nonhealing leg ulcers presented to the emergency department with severe pain of the left lower leg and redness that was concerning for cellulitis. She sought treatment at an outside hospital for cellulitis 2 weeks prior but left against medical advice. Symptomatic review revealed chest pain, shortness of breath, nausea, vomiting, and diarrhea. The primary team started her on intravenous clindamycin and vancomycin for the presumed infection and scheduled narcotic medications due to concerns of intractable pain in the left leg. The dermatology department was consulted after failure to improve with 1 week of systemic antibiotics.

Physical examination revealed a geometric, atrophic, purple plaque on the left anterior shin from a prior leg ulcer as well as a diffuse red-pink patch extending from the knee to the ankle. Notably, the cellulitis spared the left posterior calf resting against the sheet and had a sharp line of demarcation at the distal shin. The leg was cool to the touch while the patient was distractible. She later reported that the leg was extremely tender to palpation. Dermoscopy revealed linear red pigments within skin furrows that accentuated skin lines (Figure). These findings raised suspicions of an external manipulation. The skin was wiped with an alcohol pad that removed a shimmering pink substance consistent in appearance to a cosmetic product. The skin beneath the cellulitis appeared normal.

Dermoscopy is not a standard method to diagnose cellulitis of the skin; however, when patients present with an atypical response to appropriate care, the presumed diagnosis must be challenged. This patient had dramatized symptoms, false medical history, and numerous hospitalizations that were suspicious for factitious disorder.¹ Furthermore, the physical examination was inconsistent with the classic course of cellulitis. In this case, dermoscopy had advantages over biopsies because it was noninvasive, gave immediate feedback, and provided a macroscopic view of the morphology. Via dermoscopy, we had an objective lens to distinguish cellulitis from cosmetic product and to obtain the correct diagnosis.

It’s time for the American Contact Dermatitis Society (ACDS) Allergen of the Year! For 2021, the esteemed award goes to acetophenone azine (AA). If you have never heard of this chemical, you are not alone. Acetophenone azine has been identified in foam materials made of the copolymer ethyl-vinyl acetate (EVA). Contact allergy to AA initially was reported in 2016.¹ There are only a few European and Canadian case reports and one case series of AA contact allergy in the literature, all of which are associated with foam shin pads or shin guards, shoe insoles, and/or flip-flops.^2-6 Acetophenone azine is an important emerging allergen, and in this column, we will introduce you to AA and the sneaky places it can lurk and cause allergic contact dermatitis (ACD). We also highlight diagnosis, management, and patch testing for AA contact allergy.

AA Contact Allergy in the Literature

The first case of AA contact allergy was reported in Europe in 2016 when a 13-year-old male soccer player developed severe lower leg dermatitis and later generalized dermatitis associated with wearing foam shin guards.¹ Patch testing to standard and supplemental trays was negative or not relevant; however, the patient exhibited strong reactions when patch tested directly to a piece of the shin guard soaked in acetone, water, and ethanol. Additional testing with AA diluted in acetone, water, and petrolatum resulted in positive patch test reactions to acetone dilutions of 1%, 0.1%, 0.01%, and 0.001% and aqueous solutions of 1% and 0.1%. Chromatographic analyses with high-performance liquid chromatography (HPLC) of shin guard extracts confirmed the culprit allergen to be AA.¹

In the following months, the same clinic saw 2 more cases of AA contact allergy.² An 11-year-old male soccer player developed lower leg dermatitis and later generalized dermatitis from wearing shin guards. Months later, he also developed dermatitis on the soles of the feet, which was attributed to wearing flip-flops. Patch tests to pieces of the shin guards and flip-flops were positive; AA in acetone 0.1% and 0.01% also was positive. As you might expect, HPLC again confirmed the presence of AA in the shin guards and flip-flops. The third patient was a 12-year-old boy with dermatitis on the soles of both feet; later he also developed a generalized dermatitis. Patch testing to pieces of the insoles of his sneakers and AA in acetone 0.1% and 0.01% was positive. Again, HPLC was positive for the presence of AA in the insoles of his sneakers.²

Several more cases of AA contact allergy have been reported in the literature. A 29-year-old European male hockey player demonstrated contact allergy to the gray foam of his shin pads as well as localized leg dermatitis followed by generalized dermatitis (are you noticing a trend yet?), and later dermatitis on the soles of the feet with positive patch-test reactions to pieces of his shin pads and shoe insoles as well as AA 0.1% and 0.01% in acetone.³ A 6-year-old Canadian male soccer player presented with leg dermatitis and later generalized dermatitis and dermatitis on the soles of the feet with positive reactions to pieces of his shin pads and shoe insoles as well as to AA 1% and 0.1% in petrolatum.⁴ A 17-year-old British male (another trend, all males so far!) hockey player developed dermatitis localized to the legs and positive patch tests to the worn foam inner lining of his shin pads as well as to AA 0.1%, 0.01%, and 0.001% in acetone.⁵Finally, Darrigade et al⁶ published a case series of 6 European children with AA contact allergy associated with shin pads and shoes; all had localized leg dermatitis, and some had generalized dermatitis. Patch testing to pieces of shin pads and shoe parts as well as to AA 0.1% in petrolatum and/or acetone showed with positive reactions to the foam pieces and AA in all 6 patients.

What’s the Deal With AA?

Acetophenone azine (also known as methylphenylketazine or bis[1-phenylethylidene]hydrazine) is composed of 2 acetophenone structures and a hydrazine moiety. It has been identified in EVA foam, which can be found in sports equipment such as shin pads or shin guards, shoes, and flip-flops. Raison-Peyron et al¹ confirmed the presence of AA in EVA foam but reported that they did not know the exact reason for its presence. The authors theorized that AA might be a catalyst during EVA polymerization and also noted that it has antimicrobial and antihelminthic activity.¹ Several authors noted that AA could be a by-product of EVA synthesis and that sports equipment manufacturers might not be aware of its presence in EVA.^2,4-6 Some noted that AA concentration was higher in shin guards than in shoe insoles; they thought this explained why patients reacted first to their shin guards and were perhaps even initially sensitized to the shin guards, as well as why shoe insole contact allergy commonly was reported later or only after allergy to shin guards had already developed.^4,6

Differential Diagnosis of Shin Pad or Shin Guard Dermatitis

We would be remiss if we did not mention the appropriate differential diagnosis when shin pad or shin guard dermatitis is identified. In fact, in most cases, shin guard dermatitis results from irritant contact dermatitis from friction, heat, and/or perspiration. Acetophenone azine contact allergy is not the most likely diagnosis when your sports-savvy, shin guard–wearing patient presents with anterior lower leg dermatitis. However, when conservative therapy (eg, barrier between the shin guard and the skin, control or management of perspiration, topical corticosteroid therapy) fails, patch testing to evaluate for ACD is indicated.

Management of AA Contact Allergy

As astute readers of this column are already aware, treatment of ACD requires strict allergen avoidance. You will find that we have the same recommendations for AA contact allergy. Given that there are only a handful of cases in the literature, there are limited recommendations on practical allergen avoidance other than “don’t wear the problem shin guards, shoe insoles, or flip-flops.” However, Darrigade et al⁶ recommended wearing polyurethane shin guards and leather insoles as alternatives when AA contact allergy is suspected or confirmed. They also made it clear that thick socks worn between shin guards and the skin often are not good enough to avoid ACD because the relevant allergens may achieve skin contact despite the barrier.⁶

Patch Testing for AA Contact Allergy

Historically, ACD to shin guards or shin pads, insoles of shoes, and even flip-flops has been associated with rubber-related chemicals such as mercapto mix, thiuram mix, N-isopropyl-N’-phenyl-p-phenylenediamine, thioureas, and carbamates, as well as dyes, benzoyl peroxide, and urea formaldehyde or phenol formaldehyde resins.¹ Most of these chemicals can be tested with standard screening series or supplemental series. Patients with contact allergy to AA may have negative patch testing to screening series and/or supplemental series and may have strong positive reactions to pieces of suspected foam shin pads or shin guards, shoes, and/or flip-flops. Although Koumaki et al⁵ recommended patch testing for AA contact allergy with AA 0.1% in acetone, Besner Morin et al⁴ mentioned that petrolatum may be a more desirable vehicle because it could maintain stability for a longer period of time. In fact, a 2021 article highlighting the American Contact Dermatitis Society Allergen of the Year recommends testing with either AA 0.1% in acetone or AA 0.1% in petrolatum.⁷ Unfortunately, AA is not commercially available for purchase at the time of publication. We are hopeful that this will change in the near future.

Final Interpretation

Acetophenone azine is an emerging allergen commonly identified in EVA foam and attributed to contact allergy to shin guards or pads, soles of shoes, and flip-flops. Most cases have been reported in Europe and Canada and have been identified in young male athletes. In addition to standard patch testing, athletes with lower leg dermatitis and/or dermatitis of the soles of the feet should undergo patch testing with AA 0.1% in acetone or petrolatum and pieces of the equipment and/or footwear.

It’s time for the American Contact Dermatitis Society (ACDS) Allergen of the Year! For 2021, the esteemed award goes to acetophenone azine (AA). If you have never heard of this chemical, you are not alone. Acetophenone azine has been identified in foam materials made of the copolymer ethyl-vinyl acetate (EVA). Contact allergy to AA initially was reported in 2016.¹ There are only a few European and Canadian case reports and one case series of AA contact allergy in the literature, all of which are associated with foam shin pads or shin guards, shoe insoles, and/or flip-flops.^2-6 Acetophenone azine is an important emerging allergen, and in this column, we will introduce you to AA and the sneaky places it can lurk and cause allergic contact dermatitis (ACD). We also highlight diagnosis, management, and patch testing for AA contact allergy.

AA Contact Allergy in the Literature

The first case of AA contact allergy was reported in Europe in 2016 when a 13-year-old male soccer player developed severe lower leg dermatitis and later generalized dermatitis associated with wearing foam shin guards.¹ Patch testing to standard and supplemental trays was negative or not relevant; however, the patient exhibited strong reactions when patch tested directly to a piece of the shin guard soaked in acetone, water, and ethanol. Additional testing with AA diluted in acetone, water, and petrolatum resulted in positive patch test reactions to acetone dilutions of 1%, 0.1%, 0.01%, and 0.001% and aqueous solutions of 1% and 0.1%. Chromatographic analyses with high-performance liquid chromatography (HPLC) of shin guard extracts confirmed the culprit allergen to be AA.¹

In the following months, the same clinic saw 2 more cases of AA contact allergy.² An 11-year-old male soccer player developed lower leg dermatitis and later generalized dermatitis from wearing shin guards. Months later, he also developed dermatitis on the soles of the feet, which was attributed to wearing flip-flops. Patch tests to pieces of the shin guards and flip-flops were positive; AA in acetone 0.1% and 0.01% also was positive. As you might expect, HPLC again confirmed the presence of AA in the shin guards and flip-flops. The third patient was a 12-year-old boy with dermatitis on the soles of both feet; later he also developed a generalized dermatitis. Patch testing to pieces of the insoles of his sneakers and AA in acetone 0.1% and 0.01% was positive. Again, HPLC was positive for the presence of AA in the insoles of his sneakers.²

Several more cases of AA contact allergy have been reported in the literature. A 29-year-old European male hockey player demonstrated contact allergy to the gray foam of his shin pads as well as localized leg dermatitis followed by generalized dermatitis (are you noticing a trend yet?), and later dermatitis on the soles of the feet with positive patch-test reactions to pieces of his shin pads and shoe insoles as well as AA 0.1% and 0.01% in acetone.³ A 6-year-old Canadian male soccer player presented with leg dermatitis and later generalized dermatitis and dermatitis on the soles of the feet with positive reactions to pieces of his shin pads and shoe insoles as well as to AA 1% and 0.1% in petrolatum.⁴ A 17-year-old British male (another trend, all males so far!) hockey player developed dermatitis localized to the legs and positive patch tests to the worn foam inner lining of his shin pads as well as to AA 0.1%, 0.01%, and 0.001% in acetone.⁵Finally, Darrigade et al⁶ published a case series of 6 European children with AA contact allergy associated with shin pads and shoes; all had localized leg dermatitis, and some had generalized dermatitis. Patch testing to pieces of shin pads and shoe parts as well as to AA 0.1% in petrolatum and/or acetone showed with positive reactions to the foam pieces and AA in all 6 patients.

What’s the Deal With AA?

Acetophenone azine (also known as methylphenylketazine or bis[1-phenylethylidene]hydrazine) is composed of 2 acetophenone structures and a hydrazine moiety. It has been identified in EVA foam, which can be found in sports equipment such as shin pads or shin guards, shoes, and flip-flops. Raison-Peyron et al¹ confirmed the presence of AA in EVA foam but reported that they did not know the exact reason for its presence. The authors theorized that AA might be a catalyst during EVA polymerization and also noted that it has antimicrobial and antihelminthic activity.¹ Several authors noted that AA could be a by-product of EVA synthesis and that sports equipment manufacturers might not be aware of its presence in EVA.^2,4-6 Some noted that AA concentration was higher in shin guards than in shoe insoles; they thought this explained why patients reacted first to their shin guards and were perhaps even initially sensitized to the shin guards, as well as why shoe insole contact allergy commonly was reported later or only after allergy to shin guards had already developed.^4,6

Differential Diagnosis of Shin Pad or Shin Guard Dermatitis

We would be remiss if we did not mention the appropriate differential diagnosis when shin pad or shin guard dermatitis is identified. In fact, in most cases, shin guard dermatitis results from irritant contact dermatitis from friction, heat, and/or perspiration. Acetophenone azine contact allergy is not the most likely diagnosis when your sports-savvy, shin guard–wearing patient presents with anterior lower leg dermatitis. However, when conservative therapy (eg, barrier between the shin guard and the skin, control or management of perspiration, topical corticosteroid therapy) fails, patch testing to evaluate for ACD is indicated.

Management of AA Contact Allergy

As astute readers of this column are already aware, treatment of ACD requires strict allergen avoidance. You will find that we have the same recommendations for AA contact allergy. Given that there are only a handful of cases in the literature, there are limited recommendations on practical allergen avoidance other than “don’t wear the problem shin guards, shoe insoles, or flip-flops.” However, Darrigade et al⁶ recommended wearing polyurethane shin guards and leather insoles as alternatives when AA contact allergy is suspected or confirmed. They also made it clear that thick socks worn between shin guards and the skin often are not good enough to avoid ACD because the relevant allergens may achieve skin contact despite the barrier.⁶

Patch Testing for AA Contact Allergy

Historically, ACD to shin guards or shin pads, insoles of shoes, and even flip-flops has been associated with rubber-related chemicals such as mercapto mix, thiuram mix, N-isopropyl-N’-phenyl-p-phenylenediamine, thioureas, and carbamates, as well as dyes, benzoyl peroxide, and urea formaldehyde or phenol formaldehyde resins.¹ Most of these chemicals can be tested with standard screening series or supplemental series. Patients with contact allergy to AA may have negative patch testing to screening series and/or supplemental series and may have strong positive reactions to pieces of suspected foam shin pads or shin guards, shoes, and/or flip-flops. Although Koumaki et al⁵ recommended patch testing for AA contact allergy with AA 0.1% in acetone, Besner Morin et al⁴ mentioned that petrolatum may be a more desirable vehicle because it could maintain stability for a longer period of time. In fact, a 2021 article highlighting the American Contact Dermatitis Society Allergen of the Year recommends testing with either AA 0.1% in acetone or AA 0.1% in petrolatum.⁷ Unfortunately, AA is not commercially available for purchase at the time of publication. We are hopeful that this will change in the near future.

Final Interpretation

Acetophenone azine is an emerging allergen commonly identified in EVA foam and attributed to contact allergy to shin guards or pads, soles of shoes, and flip-flops. Most cases have been reported in Europe and Canada and have been identified in young male athletes. In addition to standard patch testing, athletes with lower leg dermatitis and/or dermatitis of the soles of the feet should undergo patch testing with AA 0.1% in acetone or petrolatum and pieces of the equipment and/or footwear.

It’s time for the American Contact Dermatitis Society (ACDS) Allergen of the Year! For 2021, the esteemed award goes to acetophenone azine (AA). If you have never heard of this chemical, you are not alone. Acetophenone azine has been identified in foam materials made of the copolymer ethyl-vinyl acetate (EVA). Contact allergy to AA initially was reported in 2016.¹ There are only a few European and Canadian case reports and one case series of AA contact allergy in the literature, all of which are associated with foam shin pads or shin guards, shoe insoles, and/or flip-flops.^2-6 Acetophenone azine is an important emerging allergen, and in this column, we will introduce you to AA and the sneaky places it can lurk and cause allergic contact dermatitis (ACD). We also highlight diagnosis, management, and patch testing for AA contact allergy.

AA Contact Allergy in the Literature

The first case of AA contact allergy was reported in Europe in 2016 when a 13-year-old male soccer player developed severe lower leg dermatitis and later generalized dermatitis associated with wearing foam shin guards.¹ Patch testing to standard and supplemental trays was negative or not relevant; however, the patient exhibited strong reactions when patch tested directly to a piece of the shin guard soaked in acetone, water, and ethanol. Additional testing with AA diluted in acetone, water, and petrolatum resulted in positive patch test reactions to acetone dilutions of 1%, 0.1%, 0.01%, and 0.001% and aqueous solutions of 1% and 0.1%. Chromatographic analyses with high-performance liquid chromatography (HPLC) of shin guard extracts confirmed the culprit allergen to be AA.¹

In the following months, the same clinic saw 2 more cases of AA contact allergy.² An 11-year-old male soccer player developed lower leg dermatitis and later generalized dermatitis from wearing shin guards. Months later, he also developed dermatitis on the soles of the feet, which was attributed to wearing flip-flops. Patch tests to pieces of the shin guards and flip-flops were positive; AA in acetone 0.1% and 0.01% also was positive. As you might expect, HPLC again confirmed the presence of AA in the shin guards and flip-flops. The third patient was a 12-year-old boy with dermatitis on the soles of both feet; later he also developed a generalized dermatitis. Patch testing to pieces of the insoles of his sneakers and AA in acetone 0.1% and 0.01% was positive. Again, HPLC was positive for the presence of AA in the insoles of his sneakers.²

Several more cases of AA contact allergy have been reported in the literature. A 29-year-old European male hockey player demonstrated contact allergy to the gray foam of his shin pads as well as localized leg dermatitis followed by generalized dermatitis (are you noticing a trend yet?), and later dermatitis on the soles of the feet with positive patch-test reactions to pieces of his shin pads and shoe insoles as well as AA 0.1% and 0.01% in acetone.³ A 6-year-old Canadian male soccer player presented with leg dermatitis and later generalized dermatitis and dermatitis on the soles of the feet with positive reactions to pieces of his shin pads and shoe insoles as well as to AA 1% and 0.1% in petrolatum.⁴ A 17-year-old British male (another trend, all males so far!) hockey player developed dermatitis localized to the legs and positive patch tests to the worn foam inner lining of his shin pads as well as to AA 0.1%, 0.01%, and 0.001% in acetone.⁵Finally, Darrigade et al⁶ published a case series of 6 European children with AA contact allergy associated with shin pads and shoes; all had localized leg dermatitis, and some had generalized dermatitis. Patch testing to pieces of shin pads and shoe parts as well as to AA 0.1% in petrolatum and/or acetone showed with positive reactions to the foam pieces and AA in all 6 patients.

What’s the Deal With AA?

Acetophenone azine (also known as methylphenylketazine or bis[1-phenylethylidene]hydrazine) is composed of 2 acetophenone structures and a hydrazine moiety. It has been identified in EVA foam, which can be found in sports equipment such as shin pads or shin guards, shoes, and flip-flops. Raison-Peyron et al¹ confirmed the presence of AA in EVA foam but reported that they did not know the exact reason for its presence. The authors theorized that AA might be a catalyst during EVA polymerization and also noted that it has antimicrobial and antihelminthic activity.¹ Several authors noted that AA could be a by-product of EVA synthesis and that sports equipment manufacturers might not be aware of its presence in EVA.^2,4-6 Some noted that AA concentration was higher in shin guards than in shoe insoles; they thought this explained why patients reacted first to their shin guards and were perhaps even initially sensitized to the shin guards, as well as why shoe insole contact allergy commonly was reported later or only after allergy to shin guards had already developed.^4,6

Differential Diagnosis of Shin Pad or Shin Guard Dermatitis

We would be remiss if we did not mention the appropriate differential diagnosis when shin pad or shin guard dermatitis is identified. In fact, in most cases, shin guard dermatitis results from irritant contact dermatitis from friction, heat, and/or perspiration. Acetophenone azine contact allergy is not the most likely diagnosis when your sports-savvy, shin guard–wearing patient presents with anterior lower leg dermatitis. However, when conservative therapy (eg, barrier between the shin guard and the skin, control or management of perspiration, topical corticosteroid therapy) fails, patch testing to evaluate for ACD is indicated.

Management of AA Contact Allergy

As astute readers of this column are already aware, treatment of ACD requires strict allergen avoidance. You will find that we have the same recommendations for AA contact allergy. Given that there are only a handful of cases in the literature, there are limited recommendations on practical allergen avoidance other than “don’t wear the problem shin guards, shoe insoles, or flip-flops.” However, Darrigade et al⁶ recommended wearing polyurethane shin guards and leather insoles as alternatives when AA contact allergy is suspected or confirmed. They also made it clear that thick socks worn between shin guards and the skin often are not good enough to avoid ACD because the relevant allergens may achieve skin contact despite the barrier.⁶

Patch Testing for AA Contact Allergy

Historically, ACD to shin guards or shin pads, insoles of shoes, and even flip-flops has been associated with rubber-related chemicals such as mercapto mix, thiuram mix, N-isopropyl-N’-phenyl-p-phenylenediamine, thioureas, and carbamates, as well as dyes, benzoyl peroxide, and urea formaldehyde or phenol formaldehyde resins.¹ Most of these chemicals can be tested with standard screening series or supplemental series. Patients with contact allergy to AA may have negative patch testing to screening series and/or supplemental series and may have strong positive reactions to pieces of suspected foam shin pads or shin guards, shoes, and/or flip-flops. Although Koumaki et al⁵ recommended patch testing for AA contact allergy with AA 0.1% in acetone, Besner Morin et al⁴ mentioned that petrolatum may be a more desirable vehicle because it could maintain stability for a longer period of time. In fact, a 2021 article highlighting the American Contact Dermatitis Society Allergen of the Year recommends testing with either AA 0.1% in acetone or AA 0.1% in petrolatum.⁷ Unfortunately, AA is not commercially available for purchase at the time of publication. We are hopeful that this will change in the near future.

Final Interpretation

Acetophenone azine is an emerging allergen commonly identified in EVA foam and attributed to contact allergy to shin guards or pads, soles of shoes, and flip-flops. Most cases have been reported in Europe and Canada and have been identified in young male athletes. In addition to standard patch testing, athletes with lower leg dermatitis and/or dermatitis of the soles of the feet should undergo patch testing with AA 0.1% in acetone or petrolatum and pieces of the equipment and/or footwear.