Contact Dermatitis

Acute generalized exanthematous pustulosis (AGEP) is an uncommon cutaneous eruption characterized by acute, extensive, nonfollicular, sterile pustules accompanied by widespread erythema, fever, and leukocytosis. The clinical hallmark is superficial, sterile, subcorneal pustular dermatosis, which typically starts on the face, axilla, and groin and then progresses to most of the body. Approximately 90% of AGEP cases are due to drug hypersensitivity to a newly initiated medication, while the other 10% are thought to be viral in origin.¹ Discontinuation of the offending agent may allow for complete resolution within 15 days. Agents commonly implicated in causing AGEP are antibiotics such as aminopenicillins, macrolides, and cephalosporins.² Hydroxychloroquine (HCQ) also has been reported to cause AGEP,^3-7 with resolution shortly after discontinuation of the drug,^4,6 close to the characteristic 15 days of AGEP due to alternate medications.We report an unusual case of HCQ-induced AGEP that lasted far beyond the typical 15 days. We also review other cases of HCQ-induced AGEP and possible mechanisms to explain our patient’s symptoms.

Figure 1. Acute generalized exanthematous pustulosis extending to the chest and upper extremities (A) as well as the shoulders and back (B).

Case Report

A 50-year-old woman who was previously diagnosed with rheumatoid factor seronegative, nonerosive rheumatoid arthritis, which was only moderately controlled with low-dose prednisone (5 mg once daily) after 2 months of treatment, was started on oral HCQ 200 mg twice daily by her rheumatologist. Two weeks after starting HCQ treatment, she developed a pustular exanthem that gradually spread on the back over the next 24 to 48 hours. She described the eruption initially as pruritic, but she then developed painful stinging sensations as the eruption spread. She visited her primary care physician the next day and stopped the HCQ after 14 days following a discussion with the physician. Her prednisone dosage was increased to 50 mg daily for 5 days, but by the fifth day the lesions had spread to the face, full back, shoulders, and upper chest (Figure 1). Morphologically, she presented to the dermatology clinic with innumerable 1- to 2-mm pustules with confluent erythema on the back, extending to the forearms (Figure 2). She also had scattered erythematous macules and papules on the buttocks, legs, and plantar surfaces of the feet. A biopsy taken from the right forearm demonstrated subcorneal pustular dermatosis consistent with AGEP. Prednisone 50 mg once daily was continued. She was scheduled for a follow-up in 3 days but instead went to the emergency department 1 day later due to worsening of the eruption, fever, and malaise. On examination there were multiple discrete and confluent erythematous plaques on the face that extended to the lower extremities. Pustules and scales were noted on the back. New pustules had developed on the hands and feet with intense pruritus.

On admission, her vitals were stable with mild tachycardia. Aggressive intravenous hydration was administered. Her white blood cell count was elevated at 28.3×10⁹/L (reference range, 4.5–10×10⁹/L). She was started on intravenous methylprednisolone 100 mg once daily; topical steroid wet wraps with triamcinolone 0.1% were applied to the trunk, arms, legs, and abdomen twice daily; and hydrocortisone cream 2.5% was applied to the face and intertriginous areas 3 times daily. Over the next 2 days, eruptions continued to persist and the patient reported worsening of pain despite treatment. On day 3, intravenous methylprednisolone 100 mg was switched to oral prednisone 80 mg once daily.

Over the ensuing 5 days, recurrent episodes of erythema on the back had spread to the extremities. After 1 week in the hospital, the diffuse erythema had improved and she had widespread desquamation. She was discharged and prescribed oral prednisone 80 mg once daily and topical therapy twice daily. The patient followed up in the dermatology clinic 4 days after discharge with a mildly pruritic eruption on the trunk and proximal lower extremities but otherwise was doing well. She was instructed to taper the prednisone by 10 mg every 4 days.

At a follow-up 3 weeks later, she had persistent stinging and tingling sensations, widespread xerosis, and diffuse patchy erythema primarily on the back and proximal extremities, which flared over the last week. The patient reported waxing and waning of the erythema and pruritus since being discharged from the hospital. Despite the recent flare, which was her fourth flare of cutaneous eruption, she showed marked improvement since her initial examination and 40 days after discontinuation of HCQ. She was taking prednisone 40 mg once daily and was advised to continue tapering the dose by 2 mg every 6 to 8 days as tolerated. At 81 days after AGEP onset, the eruption had resolved and the patient was back to her baseline prednisone dosage of 5 mg once daily.

Comment

Acute generalized exanthematous pustulosis is characterized by the sudden appearance of erythema and hundreds of sterile nonfollicular pustules, fever, and leukocytosis. Histologically, AGEP is composed of subcorneal and intraepidermal pustules, edema of the papillary dermis, and perivascular infiltrates of neutrophils and possible eosinophils. The pathogenesis of AGEP is thought to be due to the release of increased amounts of IL-8 by T cells, which attract and activate polymorphonuclear neutrophils.¹ Psoriasiform changes are uncommon. Clinically, AGEP is similar to pustular psoriasis but has shown to be its own distinct entity. Unlike patients with pustular psoriasis, patients with AGEP lack a personal or family history of psoriasis or arthritis, have a shorter duration of pustules and fever, and have a history of new medication administration. Other conditions to consider in the differential diagnosis include pustular psoriasis, subcorneal pustulosis, IgA pemphigus, drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome, Stevens-Johnson syndrome, and acute febrile neutrophilic dermatosis.

In AGEP, the average duration of medication exposure prior to onset varies depending on the causative agent. Antibiotics consistently have been shown to trigger symptoms after 1 day, whereas other medications, including HCQ, averaged closer to 11 days. Hydroxychloroquine is widely used to treat rheumatic and dermatologic diseases and has previously been reported to be a less common cause of AGEP³; however, a EuroSCAR study found that patients treated with HCQ were at a greater risk for AGEP.² Acute generalized exanthematous pustulosis usually follows a benign self-limiting course. Within days the eruption gradually evolves into superficial desquamation. Characteristically, removal of the offending agent typically leads to spontaneous resolution in less than 15 days. Resolution is generally without complications and, therefore, treatment is not always necessary. Death has been reported in up to 2% of cases.⁸ There are no known therapies that prevent the spread of lesions or further decline of the patient’s condition. Systemic corticosteroids often are used to treat AGEP with variable results.^1,5

Unique to our patient were recurring exacerbations of the cutaneous lesions beyond the typical 15 days for complete resolution. Even up to 40 days after discontinuation of medication, our patient continued to experience cutaneous symptoms. Other reported cases have not described patients with symptoms flaring or continuing for this extended period of time. A review of 7 external AGEP cases caused by HCQ (identified through a PubMed search of articles indexed for MEDLINE using the search terms acute generalized exanthematous pustulosis or eruption with hydroxychloroquine or plaquenil) showed resolution within 8 days to 3 weeks (Table).^3-6,8 One case report documented disease exacerbation on day 18 after tapering the methylprednisolone dose. This patient was then treated with cyclosporine and had a prompt recovery.⁵ One case of AGEP due to terbinafine reported continual symptoms for approximately 4 weeks after terbinafine discontinuation.⁹ Our patient’s continual symptoms beyond the typical 15 days may be due to the long half-life of HCQ, which is approximately 40 to 50 days. Systemic corticosteroids often are used to control severe eruptions in AGEP and were administered to our patient; however, their utility in shortening the duration or reducing the severity of the eruption has not been proven.

Conclusion

Hydroxychloroquine is a commonly used agent for dermatologic and rheumatologic conditions. The rare but severe acute adverse event of AGEP warrants caution in HCQ use. Correct diagnosis of AGEP with HCQ cessation generally is effective as therapy. Our patient demonstrated that not all cases of AGEP show rapid resolution of cutaneous symptoms after cessation of the drug. Hydroxychloroquine’s extended half-life of 40 to 50 days surpasses that of other medications known to cause AGEP and may explain our patient’s symptoms beyond the usual course.

Acute generalized exanthematous pustulosis (AGEP) is an uncommon cutaneous eruption characterized by acute, extensive, nonfollicular, sterile pustules accompanied by widespread erythema, fever, and leukocytosis. The clinical hallmark is superficial, sterile, subcorneal pustular dermatosis, which typically starts on the face, axilla, and groin and then progresses to most of the body. Approximately 90% of AGEP cases are due to drug hypersensitivity to a newly initiated medication, while the other 10% are thought to be viral in origin.¹ Discontinuation of the offending agent may allow for complete resolution within 15 days. Agents commonly implicated in causing AGEP are antibiotics such as aminopenicillins, macrolides, and cephalosporins.² Hydroxychloroquine (HCQ) also has been reported to cause AGEP,^3-7 with resolution shortly after discontinuation of the drug,^4,6 close to the characteristic 15 days of AGEP due to alternate medications.We report an unusual case of HCQ-induced AGEP that lasted far beyond the typical 15 days. We also review other cases of HCQ-induced AGEP and possible mechanisms to explain our patient’s symptoms.

Figure 1. Acute generalized exanthematous pustulosis extending to the chest and upper extremities (A) as well as the shoulders and back (B).

Case Report

A 50-year-old woman who was previously diagnosed with rheumatoid factor seronegative, nonerosive rheumatoid arthritis, which was only moderately controlled with low-dose prednisone (5 mg once daily) after 2 months of treatment, was started on oral HCQ 200 mg twice daily by her rheumatologist. Two weeks after starting HCQ treatment, she developed a pustular exanthem that gradually spread on the back over the next 24 to 48 hours. She described the eruption initially as pruritic, but she then developed painful stinging sensations as the eruption spread. She visited her primary care physician the next day and stopped the HCQ after 14 days following a discussion with the physician. Her prednisone dosage was increased to 50 mg daily for 5 days, but by the fifth day the lesions had spread to the face, full back, shoulders, and upper chest (Figure 1). Morphologically, she presented to the dermatology clinic with innumerable 1- to 2-mm pustules with confluent erythema on the back, extending to the forearms (Figure 2). She also had scattered erythematous macules and papules on the buttocks, legs, and plantar surfaces of the feet. A biopsy taken from the right forearm demonstrated subcorneal pustular dermatosis consistent with AGEP. Prednisone 50 mg once daily was continued. She was scheduled for a follow-up in 3 days but instead went to the emergency department 1 day later due to worsening of the eruption, fever, and malaise. On examination there were multiple discrete and confluent erythematous plaques on the face that extended to the lower extremities. Pustules and scales were noted on the back. New pustules had developed on the hands and feet with intense pruritus.

On admission, her vitals were stable with mild tachycardia. Aggressive intravenous hydration was administered. Her white blood cell count was elevated at 28.3×10⁹/L (reference range, 4.5–10×10⁹/L). She was started on intravenous methylprednisolone 100 mg once daily; topical steroid wet wraps with triamcinolone 0.1% were applied to the trunk, arms, legs, and abdomen twice daily; and hydrocortisone cream 2.5% was applied to the face and intertriginous areas 3 times daily. Over the next 2 days, eruptions continued to persist and the patient reported worsening of pain despite treatment. On day 3, intravenous methylprednisolone 100 mg was switched to oral prednisone 80 mg once daily.

Over the ensuing 5 days, recurrent episodes of erythema on the back had spread to the extremities. After 1 week in the hospital, the diffuse erythema had improved and she had widespread desquamation. She was discharged and prescribed oral prednisone 80 mg once daily and topical therapy twice daily. The patient followed up in the dermatology clinic 4 days after discharge with a mildly pruritic eruption on the trunk and proximal lower extremities but otherwise was doing well. She was instructed to taper the prednisone by 10 mg every 4 days.

At a follow-up 3 weeks later, she had persistent stinging and tingling sensations, widespread xerosis, and diffuse patchy erythema primarily on the back and proximal extremities, which flared over the last week. The patient reported waxing and waning of the erythema and pruritus since being discharged from the hospital. Despite the recent flare, which was her fourth flare of cutaneous eruption, she showed marked improvement since her initial examination and 40 days after discontinuation of HCQ. She was taking prednisone 40 mg once daily and was advised to continue tapering the dose by 2 mg every 6 to 8 days as tolerated. At 81 days after AGEP onset, the eruption had resolved and the patient was back to her baseline prednisone dosage of 5 mg once daily.

Comment

Acute generalized exanthematous pustulosis is characterized by the sudden appearance of erythema and hundreds of sterile nonfollicular pustules, fever, and leukocytosis. Histologically, AGEP is composed of subcorneal and intraepidermal pustules, edema of the papillary dermis, and perivascular infiltrates of neutrophils and possible eosinophils. The pathogenesis of AGEP is thought to be due to the release of increased amounts of IL-8 by T cells, which attract and activate polymorphonuclear neutrophils.¹ Psoriasiform changes are uncommon. Clinically, AGEP is similar to pustular psoriasis but has shown to be its own distinct entity. Unlike patients with pustular psoriasis, patients with AGEP lack a personal or family history of psoriasis or arthritis, have a shorter duration of pustules and fever, and have a history of new medication administration. Other conditions to consider in the differential diagnosis include pustular psoriasis, subcorneal pustulosis, IgA pemphigus, drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome, Stevens-Johnson syndrome, and acute febrile neutrophilic dermatosis.

In AGEP, the average duration of medication exposure prior to onset varies depending on the causative agent. Antibiotics consistently have been shown to trigger symptoms after 1 day, whereas other medications, including HCQ, averaged closer to 11 days. Hydroxychloroquine is widely used to treat rheumatic and dermatologic diseases and has previously been reported to be a less common cause of AGEP³; however, a EuroSCAR study found that patients treated with HCQ were at a greater risk for AGEP.² Acute generalized exanthematous pustulosis usually follows a benign self-limiting course. Within days the eruption gradually evolves into superficial desquamation. Characteristically, removal of the offending agent typically leads to spontaneous resolution in less than 15 days. Resolution is generally without complications and, therefore, treatment is not always necessary. Death has been reported in up to 2% of cases.⁸ There are no known therapies that prevent the spread of lesions or further decline of the patient’s condition. Systemic corticosteroids often are used to treat AGEP with variable results.^1,5

Unique to our patient were recurring exacerbations of the cutaneous lesions beyond the typical 15 days for complete resolution. Even up to 40 days after discontinuation of medication, our patient continued to experience cutaneous symptoms. Other reported cases have not described patients with symptoms flaring or continuing for this extended period of time. A review of 7 external AGEP cases caused by HCQ (identified through a PubMed search of articles indexed for MEDLINE using the search terms acute generalized exanthematous pustulosis or eruption with hydroxychloroquine or plaquenil) showed resolution within 8 days to 3 weeks (Table).^3-6,8 One case report documented disease exacerbation on day 18 after tapering the methylprednisolone dose. This patient was then treated with cyclosporine and had a prompt recovery.⁵ One case of AGEP due to terbinafine reported continual symptoms for approximately 4 weeks after terbinafine discontinuation.⁹ Our patient’s continual symptoms beyond the typical 15 days may be due to the long half-life of HCQ, which is approximately 40 to 50 days. Systemic corticosteroids often are used to control severe eruptions in AGEP and were administered to our patient; however, their utility in shortening the duration or reducing the severity of the eruption has not been proven.

Conclusion

Hydroxychloroquine is a commonly used agent for dermatologic and rheumatologic conditions. The rare but severe acute adverse event of AGEP warrants caution in HCQ use. Correct diagnosis of AGEP with HCQ cessation generally is effective as therapy. Our patient demonstrated that not all cases of AGEP show rapid resolution of cutaneous symptoms after cessation of the drug. Hydroxychloroquine’s extended half-life of 40 to 50 days surpasses that of other medications known to cause AGEP and may explain our patient’s symptoms beyond the usual course.

Acute generalized exanthematous pustulosis (AGEP) is an uncommon cutaneous eruption characterized by acute, extensive, nonfollicular, sterile pustules accompanied by widespread erythema, fever, and leukocytosis. The clinical hallmark is superficial, sterile, subcorneal pustular dermatosis, which typically starts on the face, axilla, and groin and then progresses to most of the body. Approximately 90% of AGEP cases are due to drug hypersensitivity to a newly initiated medication, while the other 10% are thought to be viral in origin.¹ Discontinuation of the offending agent may allow for complete resolution within 15 days. Agents commonly implicated in causing AGEP are antibiotics such as aminopenicillins, macrolides, and cephalosporins.² Hydroxychloroquine (HCQ) also has been reported to cause AGEP,^3-7 with resolution shortly after discontinuation of the drug,^4,6 close to the characteristic 15 days of AGEP due to alternate medications.We report an unusual case of HCQ-induced AGEP that lasted far beyond the typical 15 days. We also review other cases of HCQ-induced AGEP and possible mechanisms to explain our patient’s symptoms.

Figure 1. Acute generalized exanthematous pustulosis extending to the chest and upper extremities (A) as well as the shoulders and back (B).

Case Report

A 50-year-old woman who was previously diagnosed with rheumatoid factor seronegative, nonerosive rheumatoid arthritis, which was only moderately controlled with low-dose prednisone (5 mg once daily) after 2 months of treatment, was started on oral HCQ 200 mg twice daily by her rheumatologist. Two weeks after starting HCQ treatment, she developed a pustular exanthem that gradually spread on the back over the next 24 to 48 hours. She described the eruption initially as pruritic, but she then developed painful stinging sensations as the eruption spread. She visited her primary care physician the next day and stopped the HCQ after 14 days following a discussion with the physician. Her prednisone dosage was increased to 50 mg daily for 5 days, but by the fifth day the lesions had spread to the face, full back, shoulders, and upper chest (Figure 1). Morphologically, she presented to the dermatology clinic with innumerable 1- to 2-mm pustules with confluent erythema on the back, extending to the forearms (Figure 2). She also had scattered erythematous macules and papules on the buttocks, legs, and plantar surfaces of the feet. A biopsy taken from the right forearm demonstrated subcorneal pustular dermatosis consistent with AGEP. Prednisone 50 mg once daily was continued. She was scheduled for a follow-up in 3 days but instead went to the emergency department 1 day later due to worsening of the eruption, fever, and malaise. On examination there were multiple discrete and confluent erythematous plaques on the face that extended to the lower extremities. Pustules and scales were noted on the back. New pustules had developed on the hands and feet with intense pruritus.

On admission, her vitals were stable with mild tachycardia. Aggressive intravenous hydration was administered. Her white blood cell count was elevated at 28.3×10⁹/L (reference range, 4.5–10×10⁹/L). She was started on intravenous methylprednisolone 100 mg once daily; topical steroid wet wraps with triamcinolone 0.1% were applied to the trunk, arms, legs, and abdomen twice daily; and hydrocortisone cream 2.5% was applied to the face and intertriginous areas 3 times daily. Over the next 2 days, eruptions continued to persist and the patient reported worsening of pain despite treatment. On day 3, intravenous methylprednisolone 100 mg was switched to oral prednisone 80 mg once daily.

Over the ensuing 5 days, recurrent episodes of erythema on the back had spread to the extremities. After 1 week in the hospital, the diffuse erythema had improved and she had widespread desquamation. She was discharged and prescribed oral prednisone 80 mg once daily and topical therapy twice daily. The patient followed up in the dermatology clinic 4 days after discharge with a mildly pruritic eruption on the trunk and proximal lower extremities but otherwise was doing well. She was instructed to taper the prednisone by 10 mg every 4 days.

At a follow-up 3 weeks later, she had persistent stinging and tingling sensations, widespread xerosis, and diffuse patchy erythema primarily on the back and proximal extremities, which flared over the last week. The patient reported waxing and waning of the erythema and pruritus since being discharged from the hospital. Despite the recent flare, which was her fourth flare of cutaneous eruption, she showed marked improvement since her initial examination and 40 days after discontinuation of HCQ. She was taking prednisone 40 mg once daily and was advised to continue tapering the dose by 2 mg every 6 to 8 days as tolerated. At 81 days after AGEP onset, the eruption had resolved and the patient was back to her baseline prednisone dosage of 5 mg once daily.

Comment

Acute generalized exanthematous pustulosis is characterized by the sudden appearance of erythema and hundreds of sterile nonfollicular pustules, fever, and leukocytosis. Histologically, AGEP is composed of subcorneal and intraepidermal pustules, edema of the papillary dermis, and perivascular infiltrates of neutrophils and possible eosinophils. The pathogenesis of AGEP is thought to be due to the release of increased amounts of IL-8 by T cells, which attract and activate polymorphonuclear neutrophils.¹ Psoriasiform changes are uncommon. Clinically, AGEP is similar to pustular psoriasis but has shown to be its own distinct entity. Unlike patients with pustular psoriasis, patients with AGEP lack a personal or family history of psoriasis or arthritis, have a shorter duration of pustules and fever, and have a history of new medication administration. Other conditions to consider in the differential diagnosis include pustular psoriasis, subcorneal pustulosis, IgA pemphigus, drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome, Stevens-Johnson syndrome, and acute febrile neutrophilic dermatosis.

In AGEP, the average duration of medication exposure prior to onset varies depending on the causative agent. Antibiotics consistently have been shown to trigger symptoms after 1 day, whereas other medications, including HCQ, averaged closer to 11 days. Hydroxychloroquine is widely used to treat rheumatic and dermatologic diseases and has previously been reported to be a less common cause of AGEP³; however, a EuroSCAR study found that patients treated with HCQ were at a greater risk for AGEP.² Acute generalized exanthematous pustulosis usually follows a benign self-limiting course. Within days the eruption gradually evolves into superficial desquamation. Characteristically, removal of the offending agent typically leads to spontaneous resolution in less than 15 days. Resolution is generally without complications and, therefore, treatment is not always necessary. Death has been reported in up to 2% of cases.⁸ There are no known therapies that prevent the spread of lesions or further decline of the patient’s condition. Systemic corticosteroids often are used to treat AGEP with variable results.^1,5

Unique to our patient were recurring exacerbations of the cutaneous lesions beyond the typical 15 days for complete resolution. Even up to 40 days after discontinuation of medication, our patient continued to experience cutaneous symptoms. Other reported cases have not described patients with symptoms flaring or continuing for this extended period of time. A review of 7 external AGEP cases caused by HCQ (identified through a PubMed search of articles indexed for MEDLINE using the search terms acute generalized exanthematous pustulosis or eruption with hydroxychloroquine or plaquenil) showed resolution within 8 days to 3 weeks (Table).^3-6,8 One case report documented disease exacerbation on day 18 after tapering the methylprednisolone dose. This patient was then treated with cyclosporine and had a prompt recovery.⁵ One case of AGEP due to terbinafine reported continual symptoms for approximately 4 weeks after terbinafine discontinuation.⁹ Our patient’s continual symptoms beyond the typical 15 days may be due to the long half-life of HCQ, which is approximately 40 to 50 days. Systemic corticosteroids often are used to control severe eruptions in AGEP and were administered to our patient; however, their utility in shortening the duration or reducing the severity of the eruption has not been proven.

Conclusion

Hydroxychloroquine is a commonly used agent for dermatologic and rheumatologic conditions. The rare but severe acute adverse event of AGEP warrants caution in HCQ use. Correct diagnosis of AGEP with HCQ cessation generally is effective as therapy. Our patient demonstrated that not all cases of AGEP show rapid resolution of cutaneous symptoms after cessation of the drug. Hydroxychloroquine’s extended half-life of 40 to 50 days surpasses that of other medications known to cause AGEP and may explain our patient’s symptoms beyond the usual course.

Atopic dermatitis (AD), more commonly referred to as eczema, is a chronic pruritic inflammatory skin disease that frequently affects both children and adults. Atopic dermatitis is most common in urban and developed countries, with a prevalence of approximately 11% in the United States.¹ The pathophysiology of AD is complex and not fully understood, despite the increasing incidence of the disease.² A myriad of factors, including genetics, defects in the innate and adaptive immune response, and skin barrier abnormalities all contribute to the pathogenesis.^3,4 As a result of these abnormalities, patients with AD are more prone to damage from environmental irritants and allergens.

The diagnosis of AD is made clinically based on patient history and visual assessment of the skin.⁵ Atopic dermatitis follows a chronic and relapsing course characterized by severe pruritus and visible skin changes including xerosis, redness, blistering, oozing, crusting, scaling, thickening, and color change.^6,7 Due to the genetic predisposition to make IgE antibodies in response to common environmental and food antigens, patients also may develop allergic rhinitis, asthma, and food-induced anaphylaxis.^8,9 Patients also are susceptible to cutaneous viral, fungal, and bacterial infections, the most common of which is an infection with Staphylococcus aureus.¹⁰

Atopic dermatitis can have a substantial impact on quality of life, which has been revealed in studies linking chronic skin conditions to depression, impairment of self-esteem, and financial hardship.¹¹ Because skin appearance impacts how a person is initially perceived by others, patients often report feeling self-conscious about their disease and experience teasing or bullying.¹² To improve their physical appearance, patients may incur considerable medical expenses. According to 2 population-based studies comprising more than 60,000 adults aged 18 to 85 years, individuals with AD face substantial financial burdens and utilize the health care system more than those without the disease. On average, patients with AD spend $371 to $489 per year on costly out-of-pocket medical expenses and report more absences from work.¹³

Although there currently is no cure for AD, treatment is aimed at relieving its symptoms and preventing acute exacerbations as well as improving cosmetic appearance to enhance quality of life. Treatment must follow a stepwise approach, which focuses on hydrating the skin, repairing the dysfunctional epithelial barrier, and controlling inflammation. Thus, the standard of care focuses on avoiding skin irritants and triggers along with the use of moisturizers and topical corticosteroids (TCs). In patients with recurring severe disease, topical calcineurin inhibitors, phototherapy, and systemic agents also may be utilized.¹⁴

Avoiding Irritants and Triggers

Atopic dermatitis is worsened by skin contact with physical and chemical irritants. Exacerbating factors in AD include exposure to food allergens, dust, emotional stress, detergents, fragranced soaps, textiles, and ingredients in cosmetic products. Patients should be advised to use mild detergents and fragrance-free soaps and to avoid harsh materials such as wool. However, avoidance of specific ingredients in cosmetic products is not as straightforward because manufacturers are not required to disclose certain ingredients. In general, fragrances such as balsam of Peru and cinnamaldehyde, as well as preservatives such as parabens, isothiazolinones, and formaldehyde, should be avoided when selecting cosmetic products. Patients with AD should purchase fragrance-free products that are specifically formulated for sensitive skin. Additionally, patients should not apply makeup if their skin is irritated or oozing, as the flare may worsen.¹⁵

Moisturizers

Due to the impaired skin barrier function in patients with AD, regular application of fragrance-free moisturizers is essential to maintain hydration and to reduce xerosis. Various classes of moisturizers may be prescribed (eg, lotions, creams, gels, ointments) based on disease severity and patient preference. Light preparations such as lotions, creams, and gels have a high water content and generally are more appealing from a cosmetic standpoint because they do not create any residue on the skin. However, these options may require more frequent application because they are absorbed quickly. Heavy preparations such as ointments have longer-lasting effects due to their high oil content but tend to be less cosmetically appealing because of their greasiness.¹⁶

Although the amount and frequency of application of moisturizers has not been defined, liberal application several times daily is generally advised to minimize xerosis.¹⁷ Most physicians recommend applying moisturizer to the skin immediately after bathing to seal in moisture. Some patients prefer to use lotions and creams during the day because these products make the skin feel smooth and reserve the greasier ointments for nighttime application.

Topical Corticosteroids

Prescribed in conjunction with moisturizers, TCs are the mainstay of anti-inflammatory therapy in AD. Topical corticosteroids are classified into 7 groups based on potency, ranging from superpotent (class 1) to least potent (class 7). For acute AD flares, TCs should be applied daily for up to several weeks. Once the inflammation has resolved, it is recommended to apply TCs once to twice weekly to reduce the rate of relapse.¹⁸ Despite their effectiveness in the treatment of acute AD flares, TCs have a considerable side-effect profile. Potential adverse effects include skin atrophy, striae, telangiectasia, hypopigmentation, increased hair growth, steroid acne, growth retardation, and Cushing syndrome. Skin atrophy, which is the most common complication associated with TCs, results in shiny transparent skin, allowing for visualization of veins.^19,20 Although many of these side effects will resolve after discontinuing the TCs, they are aesthetically displeasing during treatment, making it crucial for physicians to educate their patients on the proper usage of TCs to prevent negative outcomes.

Topical Calcineurin Inhibitors

Topical calcineurin inhibitors (TCIs) are a class of anti-inflammatories that are used to overcome the adverse effects of TCs. They are approved as alternatives to TCs in patients who have failed to respond to other topical treatments as well as those who have developed cutaneous atrophy from the use of TCs or have AD in sensitive areas such as the face, neck, and/or skin folds. Unlike TCs, TCIs do not cause atrophy, striae, or discoloration of the skin, which makes them more desirable from a cosmetic perspective. Their mechanism of action is distinct from TCs in that they inhibit calcineurin-dependent T-cell activation, thus preventing the transcription of inflammatory cytokines.²¹ Two TCIs are currently available: tacrolimus ointment 0.03% and 0.1% concentrations for moderate to severe AD and pimecrolimus cream 1% for mild to moderate AD.²² Twice-daily application of TCIs is recommended to decrease inflammation and pruritus associated with AD. Studies also have shown that intermittent use of TCIs 3 times weekly can aid in reducing relapses.^23-25

The results from clinical trials demonstrate the rapid and continuous effects of both pimecrolimus and tacrolimus. In a controlled long-term study of adults, pimecrolimus provided significant relief of pruritus as soon as day 3 (P<.001).^26,27 Pimecrolimus also provides long-term relief by preventing disease progression to flares, which was exemplified in a study (N=713) with no flares in 51% of pimecrolimus patients at 12 months versus 28% in the conventional treatment group (P<.001).²⁸ Similarly, long-term studies of tacrolimus demonstrated an improvement of all symptoms of AD after 1 week of treatment. Maximal improvement was achieved with continued use of tacrolimus, and up to 1 year of tacrolimus use was found to be safe and effective.^29,30 Thus, TCIs have been proven to be an effective choice in maintenance therapy for AD and have a good safety profile. The most common adverse effects of TCIs are local skin reactions, such as stinging and burning at the site of application. Rare cases of skin cancer and lymphoma have been reported; however, a causal relationship has yet to be established.^31,32

Additional Therapies

Wet wrap therapy is effective for rapid control of flares and in controlling recalcitrant AD. Wet wraps function via several mechanisms; they provide a mechanical barrier against scratching, increase moisture and soften the skin, and enhance absorption of topical medications.^33,34 The following method is employed when using wet wraps: an emollient or TC is applied to the area, a tubular bandage soaked in warm water is wrapped over the area, and dry bandages are used to form the outermost layer. Although wet wrap therapy is beneficial in treating AD, it is labor intensive and may require the expertise of a nurse. Thus, unlike other therapies, which patients can easily apply without interfering with their day, wet wraps must be applied at home or in a hospital setting.

Light therapy is another effective method of controlling AD. Although multiple forms of UV phototherapy are beneficial for symptom control in AD, there is no definitive recommendation regarding the specific type of light therapy due to a lack of comparative studies. Natural sunlight, narrowband UVB, broadband UVB, UVA, oral or topical psoralen plus UVA, as well as UVA and UVB can all be utilized in the treatment of AD. However, similar to natural sunlight, artificial light therapy can cause burning, blistering, hyperpigmentation, dark spots, and wrinkles. Because society places a large emphasis on maintaining a youthful appearance, patients may be hesitant to use a treatment that could potentially advance the skin’s aging process. Thus, it is important that this therapy is properly controlled to prevent further skin damage.^35-37

When optimal topical regimens and phototherapy have failed to control AD, systemic immunomodulation therapies may be used. Currently, the most commonly used medications are cyclosporine 150 to 300 mg daily, methotrexate 7.5 to 25 mg weekly, mycophenolate mofetil 0.5 to 3 g daily, and azathioprine 1 to 3 mg/kg daily.^38,39 Decisions regarding the specific class of drugs should be based on the patient’s AD status, comorbidities, and personal preference.

Conclusion

Atopic dermatitis is a common chronic condition that can occur at any age and cause substantial physical, psychological, social, and/or emotional stress for patients and their families. Although TCs have been the standard of treatment for many years, ongoing concerns regarding their safety have led to the use of TCIs, which overcome some of the drawbacks of steroid therapy. Phototherapy and systemic immunosuppressant therapy are reserved for patients who have not responded to optimal topical therapies. Although several therapeutic avenues exist for patients, there is a need for the development of more effective and safer drugs. Furthermore, cosmetic products created specifically for patients with AD would be beneficial, as patients often struggle to select products that do not cause more harm than good. Given the complexity of the pathogenesis of AD, further research must focus on defining the specific pathways involved in the disease and targeting these pathways with therapies.

Atopic dermatitis (AD), more commonly referred to as eczema, is a chronic pruritic inflammatory skin disease that frequently affects both children and adults. Atopic dermatitis is most common in urban and developed countries, with a prevalence of approximately 11% in the United States.¹ The pathophysiology of AD is complex and not fully understood, despite the increasing incidence of the disease.² A myriad of factors, including genetics, defects in the innate and adaptive immune response, and skin barrier abnormalities all contribute to the pathogenesis.^3,4 As a result of these abnormalities, patients with AD are more prone to damage from environmental irritants and allergens.

The diagnosis of AD is made clinically based on patient history and visual assessment of the skin.⁵ Atopic dermatitis follows a chronic and relapsing course characterized by severe pruritus and visible skin changes including xerosis, redness, blistering, oozing, crusting, scaling, thickening, and color change.^6,7 Due to the genetic predisposition to make IgE antibodies in response to common environmental and food antigens, patients also may develop allergic rhinitis, asthma, and food-induced anaphylaxis.^8,9 Patients also are susceptible to cutaneous viral, fungal, and bacterial infections, the most common of which is an infection with Staphylococcus aureus.¹⁰

Atopic dermatitis can have a substantial impact on quality of life, which has been revealed in studies linking chronic skin conditions to depression, impairment of self-esteem, and financial hardship.¹¹ Because skin appearance impacts how a person is initially perceived by others, patients often report feeling self-conscious about their disease and experience teasing or bullying.¹² To improve their physical appearance, patients may incur considerable medical expenses. According to 2 population-based studies comprising more than 60,000 adults aged 18 to 85 years, individuals with AD face substantial financial burdens and utilize the health care system more than those without the disease. On average, patients with AD spend $371 to $489 per year on costly out-of-pocket medical expenses and report more absences from work.¹³

Although there currently is no cure for AD, treatment is aimed at relieving its symptoms and preventing acute exacerbations as well as improving cosmetic appearance to enhance quality of life. Treatment must follow a stepwise approach, which focuses on hydrating the skin, repairing the dysfunctional epithelial barrier, and controlling inflammation. Thus, the standard of care focuses on avoiding skin irritants and triggers along with the use of moisturizers and topical corticosteroids (TCs). In patients with recurring severe disease, topical calcineurin inhibitors, phototherapy, and systemic agents also may be utilized.¹⁴

Avoiding Irritants and Triggers

Atopic dermatitis is worsened by skin contact with physical and chemical irritants. Exacerbating factors in AD include exposure to food allergens, dust, emotional stress, detergents, fragranced soaps, textiles, and ingredients in cosmetic products. Patients should be advised to use mild detergents and fragrance-free soaps and to avoid harsh materials such as wool. However, avoidance of specific ingredients in cosmetic products is not as straightforward because manufacturers are not required to disclose certain ingredients. In general, fragrances such as balsam of Peru and cinnamaldehyde, as well as preservatives such as parabens, isothiazolinones, and formaldehyde, should be avoided when selecting cosmetic products. Patients with AD should purchase fragrance-free products that are specifically formulated for sensitive skin. Additionally, patients should not apply makeup if their skin is irritated or oozing, as the flare may worsen.¹⁵

Moisturizers

Due to the impaired skin barrier function in patients with AD, regular application of fragrance-free moisturizers is essential to maintain hydration and to reduce xerosis. Various classes of moisturizers may be prescribed (eg, lotions, creams, gels, ointments) based on disease severity and patient preference. Light preparations such as lotions, creams, and gels have a high water content and generally are more appealing from a cosmetic standpoint because they do not create any residue on the skin. However, these options may require more frequent application because they are absorbed quickly. Heavy preparations such as ointments have longer-lasting effects due to their high oil content but tend to be less cosmetically appealing because of their greasiness.¹⁶

Although the amount and frequency of application of moisturizers has not been defined, liberal application several times daily is generally advised to minimize xerosis.¹⁷ Most physicians recommend applying moisturizer to the skin immediately after bathing to seal in moisture. Some patients prefer to use lotions and creams during the day because these products make the skin feel smooth and reserve the greasier ointments for nighttime application.

Topical Corticosteroids

Prescribed in conjunction with moisturizers, TCs are the mainstay of anti-inflammatory therapy in AD. Topical corticosteroids are classified into 7 groups based on potency, ranging from superpotent (class 1) to least potent (class 7). For acute AD flares, TCs should be applied daily for up to several weeks. Once the inflammation has resolved, it is recommended to apply TCs once to twice weekly to reduce the rate of relapse.¹⁸ Despite their effectiveness in the treatment of acute AD flares, TCs have a considerable side-effect profile. Potential adverse effects include skin atrophy, striae, telangiectasia, hypopigmentation, increased hair growth, steroid acne, growth retardation, and Cushing syndrome. Skin atrophy, which is the most common complication associated with TCs, results in shiny transparent skin, allowing for visualization of veins.^19,20 Although many of these side effects will resolve after discontinuing the TCs, they are aesthetically displeasing during treatment, making it crucial for physicians to educate their patients on the proper usage of TCs to prevent negative outcomes.

Topical Calcineurin Inhibitors

Topical calcineurin inhibitors (TCIs) are a class of anti-inflammatories that are used to overcome the adverse effects of TCs. They are approved as alternatives to TCs in patients who have failed to respond to other topical treatments as well as those who have developed cutaneous atrophy from the use of TCs or have AD in sensitive areas such as the face, neck, and/or skin folds. Unlike TCs, TCIs do not cause atrophy, striae, or discoloration of the skin, which makes them more desirable from a cosmetic perspective. Their mechanism of action is distinct from TCs in that they inhibit calcineurin-dependent T-cell activation, thus preventing the transcription of inflammatory cytokines.²¹ Two TCIs are currently available: tacrolimus ointment 0.03% and 0.1% concentrations for moderate to severe AD and pimecrolimus cream 1% for mild to moderate AD.²² Twice-daily application of TCIs is recommended to decrease inflammation and pruritus associated with AD. Studies also have shown that intermittent use of TCIs 3 times weekly can aid in reducing relapses.^23-25

The results from clinical trials demonstrate the rapid and continuous effects of both pimecrolimus and tacrolimus. In a controlled long-term study of adults, pimecrolimus provided significant relief of pruritus as soon as day 3 (P<.001).^26,27 Pimecrolimus also provides long-term relief by preventing disease progression to flares, which was exemplified in a study (N=713) with no flares in 51% of pimecrolimus patients at 12 months versus 28% in the conventional treatment group (P<.001).²⁸ Similarly, long-term studies of tacrolimus demonstrated an improvement of all symptoms of AD after 1 week of treatment. Maximal improvement was achieved with continued use of tacrolimus, and up to 1 year of tacrolimus use was found to be safe and effective.^29,30 Thus, TCIs have been proven to be an effective choice in maintenance therapy for AD and have a good safety profile. The most common adverse effects of TCIs are local skin reactions, such as stinging and burning at the site of application. Rare cases of skin cancer and lymphoma have been reported; however, a causal relationship has yet to be established.^31,32

Additional Therapies

Wet wrap therapy is effective for rapid control of flares and in controlling recalcitrant AD. Wet wraps function via several mechanisms; they provide a mechanical barrier against scratching, increase moisture and soften the skin, and enhance absorption of topical medications.^33,34 The following method is employed when using wet wraps: an emollient or TC is applied to the area, a tubular bandage soaked in warm water is wrapped over the area, and dry bandages are used to form the outermost layer. Although wet wrap therapy is beneficial in treating AD, it is labor intensive and may require the expertise of a nurse. Thus, unlike other therapies, which patients can easily apply without interfering with their day, wet wraps must be applied at home or in a hospital setting.

Light therapy is another effective method of controlling AD. Although multiple forms of UV phototherapy are beneficial for symptom control in AD, there is no definitive recommendation regarding the specific type of light therapy due to a lack of comparative studies. Natural sunlight, narrowband UVB, broadband UVB, UVA, oral or topical psoralen plus UVA, as well as UVA and UVB can all be utilized in the treatment of AD. However, similar to natural sunlight, artificial light therapy can cause burning, blistering, hyperpigmentation, dark spots, and wrinkles. Because society places a large emphasis on maintaining a youthful appearance, patients may be hesitant to use a treatment that could potentially advance the skin’s aging process. Thus, it is important that this therapy is properly controlled to prevent further skin damage.^35-37

When optimal topical regimens and phototherapy have failed to control AD, systemic immunomodulation therapies may be used. Currently, the most commonly used medications are cyclosporine 150 to 300 mg daily, methotrexate 7.5 to 25 mg weekly, mycophenolate mofetil 0.5 to 3 g daily, and azathioprine 1 to 3 mg/kg daily.^38,39 Decisions regarding the specific class of drugs should be based on the patient’s AD status, comorbidities, and personal preference.

Conclusion

Atopic dermatitis is a common chronic condition that can occur at any age and cause substantial physical, psychological, social, and/or emotional stress for patients and their families. Although TCs have been the standard of treatment for many years, ongoing concerns regarding their safety have led to the use of TCIs, which overcome some of the drawbacks of steroid therapy. Phototherapy and systemic immunosuppressant therapy are reserved for patients who have not responded to optimal topical therapies. Although several therapeutic avenues exist for patients, there is a need for the development of more effective and safer drugs. Furthermore, cosmetic products created specifically for patients with AD would be beneficial, as patients often struggle to select products that do not cause more harm than good. Given the complexity of the pathogenesis of AD, further research must focus on defining the specific pathways involved in the disease and targeting these pathways with therapies.

Atopic dermatitis (AD), more commonly referred to as eczema, is a chronic pruritic inflammatory skin disease that frequently affects both children and adults. Atopic dermatitis is most common in urban and developed countries, with a prevalence of approximately 11% in the United States.¹ The pathophysiology of AD is complex and not fully understood, despite the increasing incidence of the disease.² A myriad of factors, including genetics, defects in the innate and adaptive immune response, and skin barrier abnormalities all contribute to the pathogenesis.^3,4 As a result of these abnormalities, patients with AD are more prone to damage from environmental irritants and allergens.

The diagnosis of AD is made clinically based on patient history and visual assessment of the skin.⁵ Atopic dermatitis follows a chronic and relapsing course characterized by severe pruritus and visible skin changes including xerosis, redness, blistering, oozing, crusting, scaling, thickening, and color change.^6,7 Due to the genetic predisposition to make IgE antibodies in response to common environmental and food antigens, patients also may develop allergic rhinitis, asthma, and food-induced anaphylaxis.^8,9 Patients also are susceptible to cutaneous viral, fungal, and bacterial infections, the most common of which is an infection with Staphylococcus aureus.¹⁰

Atopic dermatitis can have a substantial impact on quality of life, which has been revealed in studies linking chronic skin conditions to depression, impairment of self-esteem, and financial hardship.¹¹ Because skin appearance impacts how a person is initially perceived by others, patients often report feeling self-conscious about their disease and experience teasing or bullying.¹² To improve their physical appearance, patients may incur considerable medical expenses. According to 2 population-based studies comprising more than 60,000 adults aged 18 to 85 years, individuals with AD face substantial financial burdens and utilize the health care system more than those without the disease. On average, patients with AD spend $371 to $489 per year on costly out-of-pocket medical expenses and report more absences from work.¹³

Although there currently is no cure for AD, treatment is aimed at relieving its symptoms and preventing acute exacerbations as well as improving cosmetic appearance to enhance quality of life. Treatment must follow a stepwise approach, which focuses on hydrating the skin, repairing the dysfunctional epithelial barrier, and controlling inflammation. Thus, the standard of care focuses on avoiding skin irritants and triggers along with the use of moisturizers and topical corticosteroids (TCs). In patients with recurring severe disease, topical calcineurin inhibitors, phototherapy, and systemic agents also may be utilized.¹⁴

Avoiding Irritants and Triggers

Atopic dermatitis is worsened by skin contact with physical and chemical irritants. Exacerbating factors in AD include exposure to food allergens, dust, emotional stress, detergents, fragranced soaps, textiles, and ingredients in cosmetic products. Patients should be advised to use mild detergents and fragrance-free soaps and to avoid harsh materials such as wool. However, avoidance of specific ingredients in cosmetic products is not as straightforward because manufacturers are not required to disclose certain ingredients. In general, fragrances such as balsam of Peru and cinnamaldehyde, as well as preservatives such as parabens, isothiazolinones, and formaldehyde, should be avoided when selecting cosmetic products. Patients with AD should purchase fragrance-free products that are specifically formulated for sensitive skin. Additionally, patients should not apply makeup if their skin is irritated or oozing, as the flare may worsen.¹⁵

Moisturizers

Due to the impaired skin barrier function in patients with AD, regular application of fragrance-free moisturizers is essential to maintain hydration and to reduce xerosis. Various classes of moisturizers may be prescribed (eg, lotions, creams, gels, ointments) based on disease severity and patient preference. Light preparations such as lotions, creams, and gels have a high water content and generally are more appealing from a cosmetic standpoint because they do not create any residue on the skin. However, these options may require more frequent application because they are absorbed quickly. Heavy preparations such as ointments have longer-lasting effects due to their high oil content but tend to be less cosmetically appealing because of their greasiness.¹⁶

Although the amount and frequency of application of moisturizers has not been defined, liberal application several times daily is generally advised to minimize xerosis.¹⁷ Most physicians recommend applying moisturizer to the skin immediately after bathing to seal in moisture. Some patients prefer to use lotions and creams during the day because these products make the skin feel smooth and reserve the greasier ointments for nighttime application.

Topical Corticosteroids

Prescribed in conjunction with moisturizers, TCs are the mainstay of anti-inflammatory therapy in AD. Topical corticosteroids are classified into 7 groups based on potency, ranging from superpotent (class 1) to least potent (class 7). For acute AD flares, TCs should be applied daily for up to several weeks. Once the inflammation has resolved, it is recommended to apply TCs once to twice weekly to reduce the rate of relapse.¹⁸ Despite their effectiveness in the treatment of acute AD flares, TCs have a considerable side-effect profile. Potential adverse effects include skin atrophy, striae, telangiectasia, hypopigmentation, increased hair growth, steroid acne, growth retardation, and Cushing syndrome. Skin atrophy, which is the most common complication associated with TCs, results in shiny transparent skin, allowing for visualization of veins.^19,20 Although many of these side effects will resolve after discontinuing the TCs, they are aesthetically displeasing during treatment, making it crucial for physicians to educate their patients on the proper usage of TCs to prevent negative outcomes.

Topical Calcineurin Inhibitors

Topical calcineurin inhibitors (TCIs) are a class of anti-inflammatories that are used to overcome the adverse effects of TCs. They are approved as alternatives to TCs in patients who have failed to respond to other topical treatments as well as those who have developed cutaneous atrophy from the use of TCs or have AD in sensitive areas such as the face, neck, and/or skin folds. Unlike TCs, TCIs do not cause atrophy, striae, or discoloration of the skin, which makes them more desirable from a cosmetic perspective. Their mechanism of action is distinct from TCs in that they inhibit calcineurin-dependent T-cell activation, thus preventing the transcription of inflammatory cytokines.²¹ Two TCIs are currently available: tacrolimus ointment 0.03% and 0.1% concentrations for moderate to severe AD and pimecrolimus cream 1% for mild to moderate AD.²² Twice-daily application of TCIs is recommended to decrease inflammation and pruritus associated with AD. Studies also have shown that intermittent use of TCIs 3 times weekly can aid in reducing relapses.^23-25

The results from clinical trials demonstrate the rapid and continuous effects of both pimecrolimus and tacrolimus. In a controlled long-term study of adults, pimecrolimus provided significant relief of pruritus as soon as day 3 (P<.001).^26,27 Pimecrolimus also provides long-term relief by preventing disease progression to flares, which was exemplified in a study (N=713) with no flares in 51% of pimecrolimus patients at 12 months versus 28% in the conventional treatment group (P<.001).²⁸ Similarly, long-term studies of tacrolimus demonstrated an improvement of all symptoms of AD after 1 week of treatment. Maximal improvement was achieved with continued use of tacrolimus, and up to 1 year of tacrolimus use was found to be safe and effective.^29,30 Thus, TCIs have been proven to be an effective choice in maintenance therapy for AD and have a good safety profile. The most common adverse effects of TCIs are local skin reactions, such as stinging and burning at the site of application. Rare cases of skin cancer and lymphoma have been reported; however, a causal relationship has yet to be established.^31,32

Additional Therapies

Wet wrap therapy is effective for rapid control of flares and in controlling recalcitrant AD. Wet wraps function via several mechanisms; they provide a mechanical barrier against scratching, increase moisture and soften the skin, and enhance absorption of topical medications.^33,34 The following method is employed when using wet wraps: an emollient or TC is applied to the area, a tubular bandage soaked in warm water is wrapped over the area, and dry bandages are used to form the outermost layer. Although wet wrap therapy is beneficial in treating AD, it is labor intensive and may require the expertise of a nurse. Thus, unlike other therapies, which patients can easily apply without interfering with their day, wet wraps must be applied at home or in a hospital setting.

Light therapy is another effective method of controlling AD. Although multiple forms of UV phototherapy are beneficial for symptom control in AD, there is no definitive recommendation regarding the specific type of light therapy due to a lack of comparative studies. Natural sunlight, narrowband UVB, broadband UVB, UVA, oral or topical psoralen plus UVA, as well as UVA and UVB can all be utilized in the treatment of AD. However, similar to natural sunlight, artificial light therapy can cause burning, blistering, hyperpigmentation, dark spots, and wrinkles. Because society places a large emphasis on maintaining a youthful appearance, patients may be hesitant to use a treatment that could potentially advance the skin’s aging process. Thus, it is important that this therapy is properly controlled to prevent further skin damage.^35-37

When optimal topical regimens and phototherapy have failed to control AD, systemic immunomodulation therapies may be used. Currently, the most commonly used medications are cyclosporine 150 to 300 mg daily, methotrexate 7.5 to 25 mg weekly, mycophenolate mofetil 0.5 to 3 g daily, and azathioprine 1 to 3 mg/kg daily.^38,39 Decisions regarding the specific class of drugs should be based on the patient’s AD status, comorbidities, and personal preference.

Conclusion

Atopic dermatitis is a common chronic condition that can occur at any age and cause substantial physical, psychological, social, and/or emotional stress for patients and their families. Although TCs have been the standard of treatment for many years, ongoing concerns regarding their safety have led to the use of TCIs, which overcome some of the drawbacks of steroid therapy. Phototherapy and systemic immunosuppressant therapy are reserved for patients who have not responded to optimal topical therapies. Although several therapeutic avenues exist for patients, there is a need for the development of more effective and safer drugs. Furthermore, cosmetic products created specifically for patients with AD would be beneficial, as patients often struggle to select products that do not cause more harm than good. Given the complexity of the pathogenesis of AD, further research must focus on defining the specific pathways involved in the disease and targeting these pathways with therapies.

The Diagnosis: Acquired Acrodermatitis Enteropathica

Acquired acrodermatitis enteropathica (AAE) is a rare disorder caused by severe zinc deficiency. Although acrodermatitis enteropathica is an autosomal-recessive disorder that typically manifests in infancy, AAE also can result from poor zinc intake, impaired absorption, or accelerated losses. There are reports of AAE in patients with zinc-deficient diets,¹ eating disorders,² bariatric and other gastrointestinal surgeries,³ malabsorptive diseases,⁴ and nephrotic syndrome.⁵

Zinc plays an important role in DNA and RNA synthesis, reactive oxygen species attenuation, and energy metabolism, allowing for proper wound healing, skin differentiation, and proliferation.⁶ Zinc is found in most foods, but animal protein contains higher concentrations (Table).⁷ Approximately 85% of zinc is stored in muscles and bones, with only a small amount of accessible zinc available in the liver. Liver stores can be depleted as quickly as 1 week.⁸ Total parenteral nutrition without trace element supplementation can quickly predispose patients to AAE.

Diagnosis of this condition requires triangulation of clinical presentation, histopathology examination, and laboratory findings. Acrodermatitis enteropathica typically is characterized by dermatitis, diarrhea, and epidermal appendage findings. In its early stages, the dermatitis often manifests with angular cheilitis and paronychia.⁹ Patients then develop erythema, erosions, and occasionally vesicles or psoriasiform plaques in periorificial, perineal, and acral sites (Figure 1). Epidermal appendage effects include generalized alopecia and thinning nails with white transverse ridges. Although dermatologic and gastrointestinal manifestations are the most obvious, severe AAE may cause other symptoms, including mental slowing, hypogonadism, and impaired immune function.⁹

Histopathology of AAE skin lesions is similar to other nutritional deficiencies. Early changes are more specific to deficiency dermatitis and include cytoplasmic pallor and ballooning degeneration of keratinocytes in the stratum spinosum and granulosum.⁹ Necrolysis results in confluent keratinocyte necrosis developing into subcorneal bulla. Later in the disease course, the presentation becomes psoriasiform with keratinocyte dyskeratosis and confluent parakeratosis¹⁰ (Figure 2). Dermal edema with dilated tortuous vessels and a neutrophilic infiltrate may be present throughout disease progression.

Common laboratory abnormalities used to confirm zinc deficiency are decreased plasma zinc and alkaline phosphatase levels. Plasma zinc levels should be drawn after fasting because zinc levels decrease after food intake.⁹ Concurrent albumin levels should be drawn to correct for low levels caused by hypoalbuminemia. Acquired acrodermatitis enteropathica has been seen in patients with only mildly decreased plasma zinc levels or even zinc levels within reference range.¹¹ Alkaline phosphatase metalloenzyme synthesis requires zinc and a decreased level suggests zinc deficiency even with a plasma zinc level within reference range. Alkaline phosphatase levels usually can be ascertained in a matter of hours, while the zinc levels take much longer to result.

Acquired acrodermatitis enteropathica is treated with oral elemental zinc supplementation at 1 to 2 mg/kg daily.¹² Diarrhea typically resolves within 24 hours, but skin lesions heal in 1 to 2 weeks or longer. Although there is no consensus on when to discontinue zinc replacement therapy, therapy generally is not lifelong. Once the patient is zinc replete and the inciting factor has resolved, patients can discontinue supplementation without risk for recurrence.

Trace elements had not been added to our patient’s total parenteral nutrition prior to admission. Basic nutrition laboratory results and zinc levels returned markedly low: 14 μg/dL (reference range, 60–120 μg/dL). Alkaline phosphatase, a zinc-dependent protein, also was low at 12 U/L (reference range, 40–150 U/L). We added trace elements and vitamins and began empiric zinc replacement with 440 mg oral zinc sulfate daily (100 mg elemental zinc). Cephalexin was prescribed for impetiginized skin lesions. The patient noted skin improvement after 3 days on zinc replacement therapy.

The Diagnosis: Acquired Acrodermatitis Enteropathica

Acquired acrodermatitis enteropathica (AAE) is a rare disorder caused by severe zinc deficiency. Although acrodermatitis enteropathica is an autosomal-recessive disorder that typically manifests in infancy, AAE also can result from poor zinc intake, impaired absorption, or accelerated losses. There are reports of AAE in patients with zinc-deficient diets,¹ eating disorders,² bariatric and other gastrointestinal surgeries,³ malabsorptive diseases,⁴ and nephrotic syndrome.⁵

Zinc plays an important role in DNA and RNA synthesis, reactive oxygen species attenuation, and energy metabolism, allowing for proper wound healing, skin differentiation, and proliferation.⁶ Zinc is found in most foods, but animal protein contains higher concentrations (Table).⁷ Approximately 85% of zinc is stored in muscles and bones, with only a small amount of accessible zinc available in the liver. Liver stores can be depleted as quickly as 1 week.⁸ Total parenteral nutrition without trace element supplementation can quickly predispose patients to AAE.

Diagnosis of this condition requires triangulation of clinical presentation, histopathology examination, and laboratory findings. Acrodermatitis enteropathica typically is characterized by dermatitis, diarrhea, and epidermal appendage findings. In its early stages, the dermatitis often manifests with angular cheilitis and paronychia.⁹ Patients then develop erythema, erosions, and occasionally vesicles or psoriasiform plaques in periorificial, perineal, and acral sites (Figure 1). Epidermal appendage effects include generalized alopecia and thinning nails with white transverse ridges. Although dermatologic and gastrointestinal manifestations are the most obvious, severe AAE may cause other symptoms, including mental slowing, hypogonadism, and impaired immune function.⁹

Histopathology of AAE skin lesions is similar to other nutritional deficiencies. Early changes are more specific to deficiency dermatitis and include cytoplasmic pallor and ballooning degeneration of keratinocytes in the stratum spinosum and granulosum.⁹ Necrolysis results in confluent keratinocyte necrosis developing into subcorneal bulla. Later in the disease course, the presentation becomes psoriasiform with keratinocyte dyskeratosis and confluent parakeratosis¹⁰ (Figure 2). Dermal edema with dilated tortuous vessels and a neutrophilic infiltrate may be present throughout disease progression.

Common laboratory abnormalities used to confirm zinc deficiency are decreased plasma zinc and alkaline phosphatase levels. Plasma zinc levels should be drawn after fasting because zinc levels decrease after food intake.⁹ Concurrent albumin levels should be drawn to correct for low levels caused by hypoalbuminemia. Acquired acrodermatitis enteropathica has been seen in patients with only mildly decreased plasma zinc levels or even zinc levels within reference range.¹¹ Alkaline phosphatase metalloenzyme synthesis requires zinc and a decreased level suggests zinc deficiency even with a plasma zinc level within reference range. Alkaline phosphatase levels usually can be ascertained in a matter of hours, while the zinc levels take much longer to result.

Acquired acrodermatitis enteropathica is treated with oral elemental zinc supplementation at 1 to 2 mg/kg daily.¹² Diarrhea typically resolves within 24 hours, but skin lesions heal in 1 to 2 weeks or longer. Although there is no consensus on when to discontinue zinc replacement therapy, therapy generally is not lifelong. Once the patient is zinc replete and the inciting factor has resolved, patients can discontinue supplementation without risk for recurrence.

Trace elements had not been added to our patient’s total parenteral nutrition prior to admission. Basic nutrition laboratory results and zinc levels returned markedly low: 14 μg/dL (reference range, 60–120 μg/dL). Alkaline phosphatase, a zinc-dependent protein, also was low at 12 U/L (reference range, 40–150 U/L). We added trace elements and vitamins and began empiric zinc replacement with 440 mg oral zinc sulfate daily (100 mg elemental zinc). Cephalexin was prescribed for impetiginized skin lesions. The patient noted skin improvement after 3 days on zinc replacement therapy.

The Diagnosis: Acquired Acrodermatitis Enteropathica

Acquired acrodermatitis enteropathica (AAE) is a rare disorder caused by severe zinc deficiency. Although acrodermatitis enteropathica is an autosomal-recessive disorder that typically manifests in infancy, AAE also can result from poor zinc intake, impaired absorption, or accelerated losses. There are reports of AAE in patients with zinc-deficient diets,¹ eating disorders,² bariatric and other gastrointestinal surgeries,³ malabsorptive diseases,⁴ and nephrotic syndrome.⁵

Zinc plays an important role in DNA and RNA synthesis, reactive oxygen species attenuation, and energy metabolism, allowing for proper wound healing, skin differentiation, and proliferation.⁶ Zinc is found in most foods, but animal protein contains higher concentrations (Table).⁷ Approximately 85% of zinc is stored in muscles and bones, with only a small amount of accessible zinc available in the liver. Liver stores can be depleted as quickly as 1 week.⁸ Total parenteral nutrition without trace element supplementation can quickly predispose patients to AAE.

Diagnosis of this condition requires triangulation of clinical presentation, histopathology examination, and laboratory findings. Acrodermatitis enteropathica typically is characterized by dermatitis, diarrhea, and epidermal appendage findings. In its early stages, the dermatitis often manifests with angular cheilitis and paronychia.⁹ Patients then develop erythema, erosions, and occasionally vesicles or psoriasiform plaques in periorificial, perineal, and acral sites (Figure 1). Epidermal appendage effects include generalized alopecia and thinning nails with white transverse ridges. Although dermatologic and gastrointestinal manifestations are the most obvious, severe AAE may cause other symptoms, including mental slowing, hypogonadism, and impaired immune function.⁹

Histopathology of AAE skin lesions is similar to other nutritional deficiencies. Early changes are more specific to deficiency dermatitis and include cytoplasmic pallor and ballooning degeneration of keratinocytes in the stratum spinosum and granulosum.⁹ Necrolysis results in confluent keratinocyte necrosis developing into subcorneal bulla. Later in the disease course, the presentation becomes psoriasiform with keratinocyte dyskeratosis and confluent parakeratosis¹⁰ (Figure 2). Dermal edema with dilated tortuous vessels and a neutrophilic infiltrate may be present throughout disease progression.

Common laboratory abnormalities used to confirm zinc deficiency are decreased plasma zinc and alkaline phosphatase levels. Plasma zinc levels should be drawn after fasting because zinc levels decrease after food intake.⁹ Concurrent albumin levels should be drawn to correct for low levels caused by hypoalbuminemia. Acquired acrodermatitis enteropathica has been seen in patients with only mildly decreased plasma zinc levels or even zinc levels within reference range.¹¹ Alkaline phosphatase metalloenzyme synthesis requires zinc and a decreased level suggests zinc deficiency even with a plasma zinc level within reference range. Alkaline phosphatase levels usually can be ascertained in a matter of hours, while the zinc levels take much longer to result.

Acquired acrodermatitis enteropathica is treated with oral elemental zinc supplementation at 1 to 2 mg/kg daily.¹² Diarrhea typically resolves within 24 hours, but skin lesions heal in 1 to 2 weeks or longer. Although there is no consensus on when to discontinue zinc replacement therapy, therapy generally is not lifelong. Once the patient is zinc replete and the inciting factor has resolved, patients can discontinue supplementation without risk for recurrence.

Trace elements had not been added to our patient’s total parenteral nutrition prior to admission. Basic nutrition laboratory results and zinc levels returned markedly low: 14 μg/dL (reference range, 60–120 μg/dL). Alkaline phosphatase, a zinc-dependent protein, also was low at 12 U/L (reference range, 40–150 U/L). We added trace elements and vitamins and began empiric zinc replacement with 440 mg oral zinc sulfate daily (100 mg elemental zinc). Cephalexin was prescribed for impetiginized skin lesions. The patient noted skin improvement after 3 days on zinc replacement therapy.

Review the PDF of the fact sheet on allergic contact dermatitis

Practice Questions

1. The most common allergen of hand dermatitis in hairdressers can cross-react with which of the following allergens?

a. benzocaine
b. para-aminobenzoic acid
c. procaine
d. sulfanomides
e. all of the above

2. Patients with a documented allergy to quaternium-15 should avoid all of the following ingredients except:

a. bronopol
b. diazolidinyl urea
c. DMDM hydantoin
d. imidazolidinyl urea
e. paraben mix

3. Which of the following is a screening agent for hydrocortisone allergy?

a. budesonide
b. clobetasol
c. desoximetasone
d. paraben mix
e. tixocortol pivalate

4. This allergen often is found in black synthetic henna tattoos:

a. paraben mix
b. potassium dichromate
c. PPD
d. quaternium-15
e. thimerosol

5. A patient with a documented allergy to paraben mix also should avoid the following agent:

a. bronopol
b. diazolidinyl urea
c. DMDM hydantoin
d. PPD
e. thiuram mix

Practice Question Answers

1. The most common allergen of hand dermatitis in hairdressers can cross-react with which of the following allergens?

a. benzocaine
b. para-aminobenzoic acid
c. procaine
d. sulfanomides
e. all of the above

2. Patients with a documented allergy to quaternium-15 should avoid all of the following ingredients except:

a. bronopol
b. diazolidinyl urea
c. DMDM hydantoin
d. imidazolidinyl urea
e. paraben mix

3. Which of the following is a screening agent for hydrocortisone allergy?

a. budesonide
b. clobetasol
c. desoximetasone
d. paraben mix
e. tixocortol pivalate

4. This allergen often is found in black synthetic henna tattoos:

a. paraben mix
b. potassium dichromate
c. PPD
d. quaternium-15
e. thimerosol

5. A patient with a documented allergy to paraben mix also should avoid the following agent:

a. bronopol
b. diazolidinyl urea
c. DMDM hydantoin
d. PPD
e. thiuram mix

Review the PDF of the fact sheet on allergic contact dermatitis

Practice Questions

1. The most common allergen of hand dermatitis in hairdressers can cross-react with which of the following allergens?

a. benzocaine
b. para-aminobenzoic acid
c. procaine
d. sulfanomides
e. all of the above

2. Patients with a documented allergy to quaternium-15 should avoid all of the following ingredients except:

a. bronopol
b. diazolidinyl urea
c. DMDM hydantoin
d. imidazolidinyl urea
e. paraben mix

3. Which of the following is a screening agent for hydrocortisone allergy?

a. budesonide
b. clobetasol
c. desoximetasone
d. paraben mix
e. tixocortol pivalate

4. This allergen often is found in black synthetic henna tattoos:

a. paraben mix
b. potassium dichromate
c. PPD
d. quaternium-15
e. thimerosol

5. A patient with a documented allergy to paraben mix also should avoid the following agent:

a. bronopol
b. diazolidinyl urea
c. DMDM hydantoin
d. PPD
e. thiuram mix

Practice Question Answers

1. The most common allergen of hand dermatitis in hairdressers can cross-react with which of the following allergens?

a. benzocaine
b. para-aminobenzoic acid
c. procaine
d. sulfanomides
e. all of the above

2. Patients with a documented allergy to quaternium-15 should avoid all of the following ingredients except:

a. bronopol
b. diazolidinyl urea
c. DMDM hydantoin
d. imidazolidinyl urea
e. paraben mix

3. Which of the following is a screening agent for hydrocortisone allergy?

a. budesonide
b. clobetasol
c. desoximetasone
d. paraben mix
e. tixocortol pivalate

4. This allergen often is found in black synthetic henna tattoos:

a. paraben mix
b. potassium dichromate
c. PPD
d. quaternium-15
e. thimerosol

5. A patient with a documented allergy to paraben mix also should avoid the following agent:

a. bronopol
b. diazolidinyl urea
c. DMDM hydantoin
d. PPD
e. thiuram mix

Review the PDF of the fact sheet on allergic contact dermatitis

Practice Questions

1. The most common allergen of hand dermatitis in hairdressers can cross-react with which of the following allergens?

a. benzocaine
b. para-aminobenzoic acid
c. procaine
d. sulfanomides
e. all of the above

2. Patients with a documented allergy to quaternium-15 should avoid all of the following ingredients except:

a. bronopol
b. diazolidinyl urea
c. DMDM hydantoin
d. imidazolidinyl urea
e. paraben mix

3. Which of the following is a screening agent for hydrocortisone allergy?

a. budesonide
b. clobetasol
c. desoximetasone
d. paraben mix
e. tixocortol pivalate

4. This allergen often is found in black synthetic henna tattoos:

a. paraben mix
b. potassium dichromate
c. PPD
d. quaternium-15
e. thimerosol

5. A patient with a documented allergy to paraben mix also should avoid the following agent:

a. bronopol
b. diazolidinyl urea
c. DMDM hydantoin
d. PPD
e. thiuram mix

Practice Question Answers

1. The most common allergen of hand dermatitis in hairdressers can cross-react with which of the following allergens?

a. benzocaine
b. para-aminobenzoic acid
c. procaine
d. sulfanomides
e. all of the above

2. Patients with a documented allergy to quaternium-15 should avoid all of the following ingredients except:

a. bronopol
b. diazolidinyl urea
c. DMDM hydantoin
d. imidazolidinyl urea
e. paraben mix

3. Which of the following is a screening agent for hydrocortisone allergy?

a. budesonide
b. clobetasol
c. desoximetasone
d. paraben mix
e. tixocortol pivalate

4. This allergen often is found in black synthetic henna tattoos:

a. paraben mix
b. potassium dichromate
c. PPD
d. quaternium-15
e. thimerosol

5. A patient with a documented allergy to paraben mix also should avoid the following agent:

a. bronopol
b. diazolidinyl urea
c. DMDM hydantoin
d. PPD
e. thiuram mix

The Diagnosis: Stinkbug Staining

After discussing management options with the patient including biopsy, we decided that we would photograph the lesion and follow-up in clinic. While dressing, the patient discovered the source of the pigment, a stinkbug, stuck to the corresponding area of the sock.

The brown marmorated stinkbug (Halyomorpha halys)(Figure) is a member of the Pentatomidae family. This insect is native to East Asia and has become an invasive species in the United States. Their presence has recently increased in the eastern United States and they have become an important agricultural pest as well as a household nuisance. Stinkbugs most commonly interact with humans during the fall and winter months when they enter homes because of cooler temperatures outdoors. They can fit into many unexpected places because of their thin profile.¹

Stinkbugs earned their name because of their defensive release of a malodorous chemical. This chemical is comprised of trans-2-decenal and trans-2-octenal, which are both aldehydes and are chemically related to formaldehyde. Based on the material safety data sheet, trans-2-decenal also may be responsible for the orange-brown color seen on the patient’s skin.² Contact dermatitis caused by direct excretion of this chemical onto human skin has been reported³; anecdotal reports of irritation in agricultural workers have been noted. Stinkbugs are becoming a more common household and agricultural pest and should be recognized as possible causes of some presentations in the dermatology clinic.

The Diagnosis: Stinkbug Staining

After discussing management options with the patient including biopsy, we decided that we would photograph the lesion and follow-up in clinic. While dressing, the patient discovered the source of the pigment, a stinkbug, stuck to the corresponding area of the sock.

The brown marmorated stinkbug (Halyomorpha halys)(Figure) is a member of the Pentatomidae family. This insect is native to East Asia and has become an invasive species in the United States. Their presence has recently increased in the eastern United States and they have become an important agricultural pest as well as a household nuisance. Stinkbugs most commonly interact with humans during the fall and winter months when they enter homes because of cooler temperatures outdoors. They can fit into many unexpected places because of their thin profile.¹

Stinkbugs earned their name because of their defensive release of a malodorous chemical. This chemical is comprised of trans-2-decenal and trans-2-octenal, which are both aldehydes and are chemically related to formaldehyde. Based on the material safety data sheet, trans-2-decenal also may be responsible for the orange-brown color seen on the patient’s skin.² Contact dermatitis caused by direct excretion of this chemical onto human skin has been reported³; anecdotal reports of irritation in agricultural workers have been noted. Stinkbugs are becoming a more common household and agricultural pest and should be recognized as possible causes of some presentations in the dermatology clinic.

The Diagnosis: Stinkbug Staining

After discussing management options with the patient including biopsy, we decided that we would photograph the lesion and follow-up in clinic. While dressing, the patient discovered the source of the pigment, a stinkbug, stuck to the corresponding area of the sock.

The brown marmorated stinkbug (Halyomorpha halys)(Figure) is a member of the Pentatomidae family. This insect is native to East Asia and has become an invasive species in the United States. Their presence has recently increased in the eastern United States and they have become an important agricultural pest as well as a household nuisance. Stinkbugs most commonly interact with humans during the fall and winter months when they enter homes because of cooler temperatures outdoors. They can fit into many unexpected places because of their thin profile.¹

Stinkbugs earned their name because of their defensive release of a malodorous chemical. This chemical is comprised of trans-2-decenal and trans-2-octenal, which are both aldehydes and are chemically related to formaldehyde. Based on the material safety data sheet, trans-2-decenal also may be responsible for the orange-brown color seen on the patient’s skin.² Contact dermatitis caused by direct excretion of this chemical onto human skin has been reported³; anecdotal reports of irritation in agricultural workers have been noted. Stinkbugs are becoming a more common household and agricultural pest and should be recognized as possible causes of some presentations in the dermatology clinic.

To the Editor:

There are a wide variety of zoonotic diseases that can be transmitted from birds to humans. Pigeons, chickens, starlings, canaries, and parakeets are known reservoirs of one particular zoonotic infection caused by the parasitic arthropod Dermanyssus gallinae.¹ Dermanyssus gallinae (chicken mite) and Ornithonyssus sylviarum (northern fowl mite) are collectively referred to as bird mites. When these mites are unable to take blood meals from birds, they search out alternative hosts²; in humans, this often leads to the development of pruritic dermatitis.³

A 30-year-old woman presented to our clinic for evaluation of severe generalized pruritus accompanied by a sensation of “bugs on the skin” of 2 weeks’ duration. She noted the pruritus worsened when she was sitting outside on her porch. A few days prior to presentation, she noticed a small, “pinpoint-sized bug” on her arm (<1 mm in size), which she brought in for identification (Figure).

The bug was identified as a bird mite (Dermanyssus gallinae) on light microscopy, which was later confirmed by a medical entomologist. After the diagnosis of bird mite dermatitis was made, the patient noted there was a nest of starlings above the light on her porch. When she later investigated the nest following the current presentation, she noted many small mites crawling around the nest. The nest was removed and her symptoms resolved completely within 2 weeks without treatment.

Bird mites belong to the Arachnida class, under the order Acari. In 1958, Williams⁴ noted D gallinae’s ability to feed on human blood. Bird mites have 5 stages of development: egg, larva, protonymph, deutonymph, and adult. Protonymphs, deutonymphs, and adults can bite humans for a blood meal.⁵ Bird mites range from 0.3 to 1 mm in length and have nonsegmented, egg-shaped bodies with 4 pairs of legs. Before taking a blood meal, bird mites generally are a translucent brown color, and appear red when engorged with blood.² Their small size makes them barely visible to the unaided eye. Of note, D gallinae and O sylviarum can be distinguished from each other based on subtle differences in morphology; for instance, the posterior genitoventral shield of O sylviarum is narrowly rounded, whereas it is broadly rounded in D gallinae. The dorsal shield of O sylviarum abruptly narrows posteriorly but is more smoothly narrowed in D gallinae.⁶ Additionally, O sylviarum tends to cause more irritating dermatitis in humans than D gallinae.³

Although they can be found worldwide, D gallinae and O sylviarum undergo optimal development at 20°C to 25°C and 70% humidity.^3,5,7 Bird mites generally develop over the course of 5 to 12 days; thus, the population of bird mites in a single nest may grow to the tens of thousands before young birds permanently leave. Dermanyssus gallinae can survive for months in abandoned nests without a blood meal, while O sylviarum can survive for several weeks.⁸ It is important to note that humans are not ideal hosts for bird mites, as they are unable to survive for extended periods of time or reproduce on human hosts.⁹

When bird mites are no longer able to obtain blood meals from nesting birds, they begin their nocturnal migration to find suitable hosts. Bird nests generally are abandoned in late spring; thus, most patients with bird mite dermatitis present to clinics with bird mite dermatitis in late spring and early summer.¹⁰ Mites often travel through cracks in doors, floors, walls, and ceilings but also can gain access to living areas through ventilation ducts and air conditioning units.¹ The mite’s bite and crawling on the skin is sometimes noticed by the patient. In general, however, intense itching is not observed until about 1 to 3 days after the mite makes contact with the skin. Patients often report that pruritus is worst at night.⁹ Papules and vesicles (bite reactions) may accompany the pruritus, and physicians commonly find bloody crust and excoriations in particularly pruritic areas.⁵ Urticarial plaques and diffuse erythema occasionally also may be present.⁹ Bird mites sometimes can be scraped from the skin and observed under light microscopy.¹¹ Blood eosinophilia is not found in bird mite dermatitis. On histologic examination, perivascular eosinophilic infiltration can be seen in the upper part of the dermis.¹²

The differential diagnosis in patients with pruritic dermatitis of unknown origin generally includes scabies, pediculosis, and dermatitis caused by other types of infestation. However, unlike scabies, bird mites do not cause burrows to form on the skin.⁹ The presence of a bird’s nest near the area where the patient lives places bird mite dermatitis higher in the differential.

Dermanyssus gallinae is a known vector of bacteria (eg, Salmonella, Shigella, Staphylococcus, Spirochaete, Rickettsia, Pasteurella, Chlamydia psittaci, Erysipelothrix rhusiopathiae) as well as the viruses that cause Eastern and Western equine encephalitis and St. Louis encephalitis. Transmission of these bacteria and viruses is known in birds, but transmission to humans has not been reported.^2,5,9,13

The management of bird mite dermatitis is straightforward. Usually mites can be successfully removed from the skin simply by bathing. Symptomatic treatment for bites with antihistamines and topical corticosteroids is sometimes but not always necessary.² Unlike scabies or lice, there is no need for treatment with lindane.¹ In terms of the prevention of additional bites, any bird nests located near living areas should be removed. Because bird mites often retreat back to nests between blood meals, insecticide sprays generally are unnecessary in interior spaces. Synthetic pyrethroids (eg, bifenthrin, cyfluthrin, cypermethrin, deltamethrin, cyhalothrin) can be used outside and in attics where nests may be located.^2,14,15 However, the ability of bird mites to develop resistance to repeated chemical control could become a future concern.¹⁶

Research regarding the true incidence of bird mite dermatitis is lacking. Some researchers believe that the condition is underreported, possibly due to its uncommon environmental origin.³ Reports of bird mite dermatitis in the literature also are scarce. Our case demonstrates the importance of taking a thorough patient history to rule out exposure to bird mites. All patients with pruritic dermatitis of unknown origin should be questioned about possible contact or proximity to bird nests. These simple questions can lead to the correct diagnosis and a treatment plan that will quickly and effectively resolve the pruritic skin eruption.

To the Editor:

There are a wide variety of zoonotic diseases that can be transmitted from birds to humans. Pigeons, chickens, starlings, canaries, and parakeets are known reservoirs of one particular zoonotic infection caused by the parasitic arthropod Dermanyssus gallinae.¹ Dermanyssus gallinae (chicken mite) and Ornithonyssus sylviarum (northern fowl mite) are collectively referred to as bird mites. When these mites are unable to take blood meals from birds, they search out alternative hosts²; in humans, this often leads to the development of pruritic dermatitis.³

A 30-year-old woman presented to our clinic for evaluation of severe generalized pruritus accompanied by a sensation of “bugs on the skin” of 2 weeks’ duration. She noted the pruritus worsened when she was sitting outside on her porch. A few days prior to presentation, she noticed a small, “pinpoint-sized bug” on her arm (<1 mm in size), which she brought in for identification (Figure).

The bug was identified as a bird mite (Dermanyssus gallinae) on light microscopy, which was later confirmed by a medical entomologist. After the diagnosis of bird mite dermatitis was made, the patient noted there was a nest of starlings above the light on her porch. When she later investigated the nest following the current presentation, she noted many small mites crawling around the nest. The nest was removed and her symptoms resolved completely within 2 weeks without treatment.

Bird mites belong to the Arachnida class, under the order Acari. In 1958, Williams⁴ noted D gallinae’s ability to feed on human blood. Bird mites have 5 stages of development: egg, larva, protonymph, deutonymph, and adult. Protonymphs, deutonymphs, and adults can bite humans for a blood meal.⁵ Bird mites range from 0.3 to 1 mm in length and have nonsegmented, egg-shaped bodies with 4 pairs of legs. Before taking a blood meal, bird mites generally are a translucent brown color, and appear red when engorged with blood.² Their small size makes them barely visible to the unaided eye. Of note, D gallinae and O sylviarum can be distinguished from each other based on subtle differences in morphology; for instance, the posterior genitoventral shield of O sylviarum is narrowly rounded, whereas it is broadly rounded in D gallinae. The dorsal shield of O sylviarum abruptly narrows posteriorly but is more smoothly narrowed in D gallinae.⁶ Additionally, O sylviarum tends to cause more irritating dermatitis in humans than D gallinae.³

Although they can be found worldwide, D gallinae and O sylviarum undergo optimal development at 20°C to 25°C and 70% humidity.^3,5,7 Bird mites generally develop over the course of 5 to 12 days; thus, the population of bird mites in a single nest may grow to the tens of thousands before young birds permanently leave. Dermanyssus gallinae can survive for months in abandoned nests without a blood meal, while O sylviarum can survive for several weeks.⁸ It is important to note that humans are not ideal hosts for bird mites, as they are unable to survive for extended periods of time or reproduce on human hosts.⁹

When bird mites are no longer able to obtain blood meals from nesting birds, they begin their nocturnal migration to find suitable hosts. Bird nests generally are abandoned in late spring; thus, most patients with bird mite dermatitis present to clinics with bird mite dermatitis in late spring and early summer.¹⁰ Mites often travel through cracks in doors, floors, walls, and ceilings but also can gain access to living areas through ventilation ducts and air conditioning units.¹ The mite’s bite and crawling on the skin is sometimes noticed by the patient. In general, however, intense itching is not observed until about 1 to 3 days after the mite makes contact with the skin. Patients often report that pruritus is worst at night.⁹ Papules and vesicles (bite reactions) may accompany the pruritus, and physicians commonly find bloody crust and excoriations in particularly pruritic areas.⁵ Urticarial plaques and diffuse erythema occasionally also may be present.⁹ Bird mites sometimes can be scraped from the skin and observed under light microscopy.¹¹ Blood eosinophilia is not found in bird mite dermatitis. On histologic examination, perivascular eosinophilic infiltration can be seen in the upper part of the dermis.¹²

The differential diagnosis in patients with pruritic dermatitis of unknown origin generally includes scabies, pediculosis, and dermatitis caused by other types of infestation. However, unlike scabies, bird mites do not cause burrows to form on the skin.⁹ The presence of a bird’s nest near the area where the patient lives places bird mite dermatitis higher in the differential.

Dermanyssus gallinae is a known vector of bacteria (eg, Salmonella, Shigella, Staphylococcus, Spirochaete, Rickettsia, Pasteurella, Chlamydia psittaci, Erysipelothrix rhusiopathiae) as well as the viruses that cause Eastern and Western equine encephalitis and St. Louis encephalitis. Transmission of these bacteria and viruses is known in birds, but transmission to humans has not been reported.^2,5,9,13

The management of bird mite dermatitis is straightforward. Usually mites can be successfully removed from the skin simply by bathing. Symptomatic treatment for bites with antihistamines and topical corticosteroids is sometimes but not always necessary.² Unlike scabies or lice, there is no need for treatment with lindane.¹ In terms of the prevention of additional bites, any bird nests located near living areas should be removed. Because bird mites often retreat back to nests between blood meals, insecticide sprays generally are unnecessary in interior spaces. Synthetic pyrethroids (eg, bifenthrin, cyfluthrin, cypermethrin, deltamethrin, cyhalothrin) can be used outside and in attics where nests may be located.^2,14,15 However, the ability of bird mites to develop resistance to repeated chemical control could become a future concern.¹⁶

Research regarding the true incidence of bird mite dermatitis is lacking. Some researchers believe that the condition is underreported, possibly due to its uncommon environmental origin.³ Reports of bird mite dermatitis in the literature also are scarce. Our case demonstrates the importance of taking a thorough patient history to rule out exposure to bird mites. All patients with pruritic dermatitis of unknown origin should be questioned about possible contact or proximity to bird nests. These simple questions can lead to the correct diagnosis and a treatment plan that will quickly and effectively resolve the pruritic skin eruption.

To the Editor:

There are a wide variety of zoonotic diseases that can be transmitted from birds to humans. Pigeons, chickens, starlings, canaries, and parakeets are known reservoirs of one particular zoonotic infection caused by the parasitic arthropod Dermanyssus gallinae.¹ Dermanyssus gallinae (chicken mite) and Ornithonyssus sylviarum (northern fowl mite) are collectively referred to as bird mites. When these mites are unable to take blood meals from birds, they search out alternative hosts²; in humans, this often leads to the development of pruritic dermatitis.³

A 30-year-old woman presented to our clinic for evaluation of severe generalized pruritus accompanied by a sensation of “bugs on the skin” of 2 weeks’ duration. She noted the pruritus worsened when she was sitting outside on her porch. A few days prior to presentation, she noticed a small, “pinpoint-sized bug” on her arm (<1 mm in size), which she brought in for identification (Figure).

The bug was identified as a bird mite (Dermanyssus gallinae) on light microscopy, which was later confirmed by a medical entomologist. After the diagnosis of bird mite dermatitis was made, the patient noted there was a nest of starlings above the light on her porch. When she later investigated the nest following the current presentation, she noted many small mites crawling around the nest. The nest was removed and her symptoms resolved completely within 2 weeks without treatment.

Bird mites belong to the Arachnida class, under the order Acari. In 1958, Williams⁴ noted D gallinae’s ability to feed on human blood. Bird mites have 5 stages of development: egg, larva, protonymph, deutonymph, and adult. Protonymphs, deutonymphs, and adults can bite humans for a blood meal.⁵ Bird mites range from 0.3 to 1 mm in length and have nonsegmented, egg-shaped bodies with 4 pairs of legs. Before taking a blood meal, bird mites generally are a translucent brown color, and appear red when engorged with blood.² Their small size makes them barely visible to the unaided eye. Of note, D gallinae and O sylviarum can be distinguished from each other based on subtle differences in morphology; for instance, the posterior genitoventral shield of O sylviarum is narrowly rounded, whereas it is broadly rounded in D gallinae. The dorsal shield of O sylviarum abruptly narrows posteriorly but is more smoothly narrowed in D gallinae.⁶ Additionally, O sylviarum tends to cause more irritating dermatitis in humans than D gallinae.³

Although they can be found worldwide, D gallinae and O sylviarum undergo optimal development at 20°C to 25°C and 70% humidity.^3,5,7 Bird mites generally develop over the course of 5 to 12 days; thus, the population of bird mites in a single nest may grow to the tens of thousands before young birds permanently leave. Dermanyssus gallinae can survive for months in abandoned nests without a blood meal, while O sylviarum can survive for several weeks.⁸ It is important to note that humans are not ideal hosts for bird mites, as they are unable to survive for extended periods of time or reproduce on human hosts.⁹

When bird mites are no longer able to obtain blood meals from nesting birds, they begin their nocturnal migration to find suitable hosts. Bird nests generally are abandoned in late spring; thus, most patients with bird mite dermatitis present to clinics with bird mite dermatitis in late spring and early summer.¹⁰ Mites often travel through cracks in doors, floors, walls, and ceilings but also can gain access to living areas through ventilation ducts and air conditioning units.¹ The mite’s bite and crawling on the skin is sometimes noticed by the patient. In general, however, intense itching is not observed until about 1 to 3 days after the mite makes contact with the skin. Patients often report that pruritus is worst at night.⁹ Papules and vesicles (bite reactions) may accompany the pruritus, and physicians commonly find bloody crust and excoriations in particularly pruritic areas.⁵ Urticarial plaques and diffuse erythema occasionally also may be present.⁹ Bird mites sometimes can be scraped from the skin and observed under light microscopy.¹¹ Blood eosinophilia is not found in bird mite dermatitis. On histologic examination, perivascular eosinophilic infiltration can be seen in the upper part of the dermis.¹²

The differential diagnosis in patients with pruritic dermatitis of unknown origin generally includes scabies, pediculosis, and dermatitis caused by other types of infestation. However, unlike scabies, bird mites do not cause burrows to form on the skin.⁹ The presence of a bird’s nest near the area where the patient lives places bird mite dermatitis higher in the differential.

Dermanyssus gallinae is a known vector of bacteria (eg, Salmonella, Shigella, Staphylococcus, Spirochaete, Rickettsia, Pasteurella, Chlamydia psittaci, Erysipelothrix rhusiopathiae) as well as the viruses that cause Eastern and Western equine encephalitis and St. Louis encephalitis. Transmission of these bacteria and viruses is known in birds, but transmission to humans has not been reported.^2,5,9,13

The management of bird mite dermatitis is straightforward. Usually mites can be successfully removed from the skin simply by bathing. Symptomatic treatment for bites with antihistamines and topical corticosteroids is sometimes but not always necessary.² Unlike scabies or lice, there is no need for treatment with lindane.¹ In terms of the prevention of additional bites, any bird nests located near living areas should be removed. Because bird mites often retreat back to nests between blood meals, insecticide sprays generally are unnecessary in interior spaces. Synthetic pyrethroids (eg, bifenthrin, cyfluthrin, cypermethrin, deltamethrin, cyhalothrin) can be used outside and in attics where nests may be located.^2,14,15 However, the ability of bird mites to develop resistance to repeated chemical control could become a future concern.¹⁶

Research regarding the true incidence of bird mite dermatitis is lacking. Some researchers believe that the condition is underreported, possibly due to its uncommon environmental origin.³ Reports of bird mite dermatitis in the literature also are scarce. Our case demonstrates the importance of taking a thorough patient history to rule out exposure to bird mites. All patients with pruritic dermatitis of unknown origin should be questioned about possible contact or proximity to bird nests. These simple questions can lead to the correct diagnosis and a treatment plan that will quickly and effectively resolve the pruritic skin eruption.

To the Editor:

A 34-year-old woman presented for evaluation of dry mouth and painless peeling of the oral mucosa of 2 months’ duration. She denied any other skin eruptions, dry eyes, vulvar or vaginal pain, or recent hair loss. A recent antinuclear antibodies test was negative. The patient’s medical history was otherwise unremarkable and her current medications included multivitamins only.

Oral examination revealed peeling gray-white tissue on the buccal mucosa and mouth floor (Figure 1). After the tissue was manually removed with a tongue blade, the mucosal base was normal in color and texture. The patient denied bruxism, biting of the mucosa or other oral trauma, or use of tobacco or nonsteroidal anti-inflammatory drugs.

Biopsies from the buccal mucosa were performed to rule out erosive lichen planus and autoimmune blistering disorders. Microscopy revealed parakeratosis and intracellular edema of the mucosa. An intraepithelial cleft at the parakeratotic surface also was present (Figure 2). Minimal inflammation was noted. Fungal staining and direct immunofluorescence were negative.

The gray-white clinical appearance of the oral mucosa resembled leukoedema, but the peeling phenomenon was uncharacteristic. Histologically, leukoedema typically has a parakeratotic and acanthotic epithelium with marked intracellular edema of the spinous layer.^1,2 Our patient demonstrated intracellular edema with the additional finding of a superficial intraepithelial cleft. These features were consistent with the observed mucosal sloughing and normal tissue base and led to our diagnosis of leukoedema with mucosal desquamation. This clinical and histologic picture was previously described in another report, but a causative agent could not be identified.²

Because leukoedema can be secondary to chemical or mechanical trauma,³ we hypothesized that the patient’s toothpaste may be the causative agent. After discontinuing use of her regular toothpaste and keeping the rest of her oral hygiene routine unchanged, the patient’s condition resolved within 2 days. The patient could not identify how long she had been using the toothpaste before symptoms began.

Our case as well as a report in the literature suggest that leukoedema with mucosal desquamation may be the result of contact mucositis to dental hygiene products.³ Reports in the dental literature suggest that a possible cause for oral mucosal desquamation is sensitivity to sodium lauryl sulfate (SLS),^1,4 an ingredient used in some toothpastes, including the one used by our patient. The patient has since switched to a non–SLS-containing toothpaste and has remained asymptomatic. She was unwilling to reintroduce an SLS-containing product for further evaluation.

Sodium lauryl sulfate is a strong anionic detergent that is commonly used as a foaming agent in dentifrices.⁴ In products with higher concentrations of SLS, the incidence of oral epithelial desquamation increases. Triclosan has been shown to protect against this irritant phenomenon.⁵ Interestingly, the SLS-containing toothpaste used by our patient did not contain triclosan.

Although leukoedema and mucosal desquamation induced by oral care products are well-described in the dental literature, it is important for dermatologists to be aware of this phenomenon, as the differential diagnosis includes autoimmune blistering disorders and erosive lichen planus, for which dermatology referral may be requested. Further studies of SLS and other toothpaste ingredients are needed to establish if sloughing of the oral mucosa is primarily caused by SLS or another ingredient.

To the Editor:

A 34-year-old woman presented for evaluation of dry mouth and painless peeling of the oral mucosa of 2 months’ duration. She denied any other skin eruptions, dry eyes, vulvar or vaginal pain, or recent hair loss. A recent antinuclear antibodies test was negative. The patient’s medical history was otherwise unremarkable and her current medications included multivitamins only.

Oral examination revealed peeling gray-white tissue on the buccal mucosa and mouth floor (Figure 1). After the tissue was manually removed with a tongue blade, the mucosal base was normal in color and texture. The patient denied bruxism, biting of the mucosa or other oral trauma, or use of tobacco or nonsteroidal anti-inflammatory drugs.

Biopsies from the buccal mucosa were performed to rule out erosive lichen planus and autoimmune blistering disorders. Microscopy revealed parakeratosis and intracellular edema of the mucosa. An intraepithelial cleft at the parakeratotic surface also was present (Figure 2). Minimal inflammation was noted. Fungal staining and direct immunofluorescence were negative.

The gray-white clinical appearance of the oral mucosa resembled leukoedema, but the peeling phenomenon was uncharacteristic. Histologically, leukoedema typically has a parakeratotic and acanthotic epithelium with marked intracellular edema of the spinous layer.^1,2 Our patient demonstrated intracellular edema with the additional finding of a superficial intraepithelial cleft. These features were consistent with the observed mucosal sloughing and normal tissue base and led to our diagnosis of leukoedema with mucosal desquamation. This clinical and histologic picture was previously described in another report, but a causative agent could not be identified.²

Because leukoedema can be secondary to chemical or mechanical trauma,³ we hypothesized that the patient’s toothpaste may be the causative agent. After discontinuing use of her regular toothpaste and keeping the rest of her oral hygiene routine unchanged, the patient’s condition resolved within 2 days. The patient could not identify how long she had been using the toothpaste before symptoms began.

Our case as well as a report in the literature suggest that leukoedema with mucosal desquamation may be the result of contact mucositis to dental hygiene products.³ Reports in the dental literature suggest that a possible cause for oral mucosal desquamation is sensitivity to sodium lauryl sulfate (SLS),^1,4 an ingredient used in some toothpastes, including the one used by our patient. The patient has since switched to a non–SLS-containing toothpaste and has remained asymptomatic. She was unwilling to reintroduce an SLS-containing product for further evaluation.

Sodium lauryl sulfate is a strong anionic detergent that is commonly used as a foaming agent in dentifrices.⁴ In products with higher concentrations of SLS, the incidence of oral epithelial desquamation increases. Triclosan has been shown to protect against this irritant phenomenon.⁵ Interestingly, the SLS-containing toothpaste used by our patient did not contain triclosan.

Although leukoedema and mucosal desquamation induced by oral care products are well-described in the dental literature, it is important for dermatologists to be aware of this phenomenon, as the differential diagnosis includes autoimmune blistering disorders and erosive lichen planus, for which dermatology referral may be requested. Further studies of SLS and other toothpaste ingredients are needed to establish if sloughing of the oral mucosa is primarily caused by SLS or another ingredient.

To the Editor:

A 34-year-old woman presented for evaluation of dry mouth and painless peeling of the oral mucosa of 2 months’ duration. She denied any other skin eruptions, dry eyes, vulvar or vaginal pain, or recent hair loss. A recent antinuclear antibodies test was negative. The patient’s medical history was otherwise unremarkable and her current medications included multivitamins only.

Oral examination revealed peeling gray-white tissue on the buccal mucosa and mouth floor (Figure 1). After the tissue was manually removed with a tongue blade, the mucosal base was normal in color and texture. The patient denied bruxism, biting of the mucosa or other oral trauma, or use of tobacco or nonsteroidal anti-inflammatory drugs.

Biopsies from the buccal mucosa were performed to rule out erosive lichen planus and autoimmune blistering disorders. Microscopy revealed parakeratosis and intracellular edema of the mucosa. An intraepithelial cleft at the parakeratotic surface also was present (Figure 2). Minimal inflammation was noted. Fungal staining and direct immunofluorescence were negative.

The gray-white clinical appearance of the oral mucosa resembled leukoedema, but the peeling phenomenon was uncharacteristic. Histologically, leukoedema typically has a parakeratotic and acanthotic epithelium with marked intracellular edema of the spinous layer.^1,2 Our patient demonstrated intracellular edema with the additional finding of a superficial intraepithelial cleft. These features were consistent with the observed mucosal sloughing and normal tissue base and led to our diagnosis of leukoedema with mucosal desquamation. This clinical and histologic picture was previously described in another report, but a causative agent could not be identified.²

Because leukoedema can be secondary to chemical or mechanical trauma,³ we hypothesized that the patient’s toothpaste may be the causative agent. After discontinuing use of her regular toothpaste and keeping the rest of her oral hygiene routine unchanged, the patient’s condition resolved within 2 days. The patient could not identify how long she had been using the toothpaste before symptoms began.

Our case as well as a report in the literature suggest that leukoedema with mucosal desquamation may be the result of contact mucositis to dental hygiene products.³ Reports in the dental literature suggest that a possible cause for oral mucosal desquamation is sensitivity to sodium lauryl sulfate (SLS),^1,4 an ingredient used in some toothpastes, including the one used by our patient. The patient has since switched to a non–SLS-containing toothpaste and has remained asymptomatic. She was unwilling to reintroduce an SLS-containing product for further evaluation.

Sodium lauryl sulfate is a strong anionic detergent that is commonly used as a foaming agent in dentifrices.⁴ In products with higher concentrations of SLS, the incidence of oral epithelial desquamation increases. Triclosan has been shown to protect against this irritant phenomenon.⁵ Interestingly, the SLS-containing toothpaste used by our patient did not contain triclosan.

Although leukoedema and mucosal desquamation induced by oral care products are well-described in the dental literature, it is important for dermatologists to be aware of this phenomenon, as the differential diagnosis includes autoimmune blistering disorders and erosive lichen planus, for which dermatology referral may be requested. Further studies of SLS and other toothpaste ingredients are needed to establish if sloughing of the oral mucosa is primarily caused by SLS or another ingredient.

The development of concomitant allergic reactions to multiple drugs is uncommon. Dermatitis induced by topical or inhaled corticosteroids (eg, budesonide) is rare,¹ and allergic reactions associated with oral nystatin, a macrolide antifungal drug, also are unusual.² We present the case of concomitant sensitization to inhaled budesonide and oral nystatin presenting as allergic contact stomatitis and systemic allergic contact dermatitis. Concomitant allergic reactions to these treatments are rare and may result in diagnostic challenges for the physician.

Case Report

A 66-year-old woman presented to the Allergy Department for evaluation of painful erosions on the oral mucosa that had developed 72 hours after she started treatment with inhaled budesonide (400 mcg every 12 hours) prescribed by her general practitioner for a nonproductive cough. Budesonide inhalation was discontinued due to suspected oral candidiasis and treatment with oral nystatin (500,000 IU every 8 hours) was started, but the erosions did not resolve. After 2 days of treatment with oral nystatin, the patient presented with erythematous macules on the abdomen and thighs as well as a larger erythematous and edematous lesion with papules and vesicles on the hypothenar eminence of the right hand. Nystatin was discontinued and the lesions turned desquamative and healed spontaneously 7 days later. The oral lesions resolved after 15 days with no further treatment.

Patch testing was conducted using a commercially standard series of contact allergens, all of which showed negative results at 48 and 96 hours except for budesonide and triamcinolone, which led to the diagnosis of allergic contact stomatitis from the inhaled budesonide. Patch testing with other corticosteroids was negative. Challenge tests with alternative corticosteroids (ie, oral methylprednisolone, parenteral betamethasone, topical mometasone furoate, inhaled fluticasone) were negative.

In order to rule out involvement of oral nystatin, a single-blind, placebo-controlled oral challenge test was performed. Eight hours after taking oral nystatin (500,000 IU), erythematous macules developed on the patient’s abdomen along with an erythematous, 3×4-cm lesion with papules on the hypothenar eminence of the right hand that was similar in appearance to the original presentation. The lesion on the hand was biopsied and histologic examination revealed spongiosis, edema of the superficial dermis, perivascular lymphocytic infiltrates, and extravasated erythrocytes with no vasculitis. Further patch testing subsequently was conducted with antifungal and antibiotic macrolides in different vehicles (ie, petrolatum, water, polyethylene glycol), as well as with excipients of the oral nystatin formulation that had been tested (Figure). Patch testing was positive with nystatin 10% in petrolatum and nystatin 30,000 IU and 90,000 IU in polyethylene glycol. Testing also were conducted in 7 healthy volunteers to rule out an irritant reaction and showed negative results. Finally, challenge tests conducted in our patient with another antifungal macrolide (parenteral amphotericin B) and antibiotic macrolides (oral clarithromycin, erythromycin, and azithromycin) were negative.

Patch and challenge test results along with the histologic findings led to diagnosis of concomitant systemic allergic contact dermatitis from oral nystatin.

Comment

Our patient presented with 2 unusual delayed hypersensitivity reactions that occurred in the same medical episode: allergic contact stomatitis from inhaled budesonide and systemic allergic contact dermatitis from oral nystatin. It is noteworthy that, despite the poor intestinal absorption of nystatin, systemic contact dermatitis to this drug has been previously described.³ Patch testing with macrolides proved useful for diagnosis in our patient, and based on the results we concluded that polyethylene glycol seemed to be the optimal vehicle for patch testing macrolide drugs versus water or petrolatum, as has been previously suggested.⁴

When a diagnosis of drug allergy is established, it is important to rule out cross-reactivity with other similar drugs by assessing if they produce the same reaction despite differences in chemical structure. Possible cross-reactivity of nystatin with other macrolides (validated on patch testing) has been reported but the tolerability was not evaluated.⁵ Our patient showed good tolerability to other macrolide drugs, both antibiotics and antifungals. Therefore, nystatin does not seem to cross-react with other structurally related drugs belonging to the macrolide group based on our results.

Corticosteroid allergies are more common than those associated with macrolides, especially contact dermatitis. Nonhalogenated corticosteroids (eg, hydrocortisone, budesonide) are most frequently associated with allergic reactions,⁶ and patch testing remains the diagnostic method of choice for the detection of delayed hypersensitivity to corticosteroids. In Europe, standard series include budesonide and tixocortol pivalate, and in the United States they include hydrocortisone 17–butyrate, triamcinolone acetonide, and clobetasol 17–propionate.⁶

To assess cross-reactivity among topical corticosteroids, patch testing with other steroids should be performed. In 1989, Coopman et al⁷ established a classification system for corticosteroids based on molecular structure, thus dividing them into 4 empirical groups: group A, hydrocortisone type; group B, acetonide type; group C, betamethasone type; and group D, ester type. The investigators hypothesized that allergic contact reactions occurred more frequently with corticosteroids belonging to the same group, while cross-reactions were uncommon between groups; however, cross-reactivity is known to occur among corticosteroids belonging to different groups in standard clinical practice, which conflicts with this claim.

Due to distinctively different behaviors among certain compounds in group D, Matura et al⁸ proposed subdividing the ester steroids into 2 groups: group D1, containing C16 methyl substitution and halogenation on the B ring, and group D2, comprising the labile ester steroids that lack both substitutions. A modified classification system including these subdivided groups is presented in the Table.⁸

In recent years, new corticosteroid drugs such as deflazacort, fluticasone propionate, and mometasone furoate have been developed, but classification of these agents has been difficult due to differences in their chemical structure, although mometasone furoate and fluticasone propionate have been included in group D1.⁹ Futhermore, the structural differences of these new steroids may mean less cross-reactivity with other steroids, which would facilitate their use in patients who are allergic to classic steroids. However, cross-reactivity between mometasone furoate and corticosteroids belonging to group B has already been described,¹⁰ which may restrict its use in patients who are allergic to other corticosteroids.

The classification of corticosteroids can provide useful information about cross-reactivity, which may help physicians in choosing an alternative drug in patients with an allergy to topical corticosteroids, but this advice about cross-reactivity does not seem to apply to systemic allergic dermatitis or immediate-type reactions to corticosteroids.¹¹ Therefore, in these types of reactions, an individualized evaluation of the sensitization profile is needed, performing wider studies with alternative corticosteroids by skin tests with late readings and challenge tests.

It is important to emphasize that hypersensitivity to corticosteroids should always be considered in the differential diagnosis along with oral candidiasis when oropharyngeal symptoms appear during inhaled corticosteroid along with oral candidiasis. We recommend that all drugs involved in a presumed allergic reaction must be systematically evaluated because an unexpected concomitant sensitization to multiple drugs could be present.

The development of concomitant allergic reactions to multiple drugs is uncommon. Dermatitis induced by topical or inhaled corticosteroids (eg, budesonide) is rare,¹ and allergic reactions associated with oral nystatin, a macrolide antifungal drug, also are unusual.² We present the case of concomitant sensitization to inhaled budesonide and oral nystatin presenting as allergic contact stomatitis and systemic allergic contact dermatitis. Concomitant allergic reactions to these treatments are rare and may result in diagnostic challenges for the physician.

Case Report

A 66-year-old woman presented to the Allergy Department for evaluation of painful erosions on the oral mucosa that had developed 72 hours after she started treatment with inhaled budesonide (400 mcg every 12 hours) prescribed by her general practitioner for a nonproductive cough. Budesonide inhalation was discontinued due to suspected oral candidiasis and treatment with oral nystatin (500,000 IU every 8 hours) was started, but the erosions did not resolve. After 2 days of treatment with oral nystatin, the patient presented with erythematous macules on the abdomen and thighs as well as a larger erythematous and edematous lesion with papules and vesicles on the hypothenar eminence of the right hand. Nystatin was discontinued and the lesions turned desquamative and healed spontaneously 7 days later. The oral lesions resolved after 15 days with no further treatment.

Patch testing was conducted using a commercially standard series of contact allergens, all of which showed negative results at 48 and 96 hours except for budesonide and triamcinolone, which led to the diagnosis of allergic contact stomatitis from the inhaled budesonide. Patch testing with other corticosteroids was negative. Challenge tests with alternative corticosteroids (ie, oral methylprednisolone, parenteral betamethasone, topical mometasone furoate, inhaled fluticasone) were negative.

In order to rule out involvement of oral nystatin, a single-blind, placebo-controlled oral challenge test was performed. Eight hours after taking oral nystatin (500,000 IU), erythematous macules developed on the patient’s abdomen along with an erythematous, 3×4-cm lesion with papules on the hypothenar eminence of the right hand that was similar in appearance to the original presentation. The lesion on the hand was biopsied and histologic examination revealed spongiosis, edema of the superficial dermis, perivascular lymphocytic infiltrates, and extravasated erythrocytes with no vasculitis. Further patch testing subsequently was conducted with antifungal and antibiotic macrolides in different vehicles (ie, petrolatum, water, polyethylene glycol), as well as with excipients of the oral nystatin formulation that had been tested (Figure). Patch testing was positive with nystatin 10% in petrolatum and nystatin 30,000 IU and 90,000 IU in polyethylene glycol. Testing also were conducted in 7 healthy volunteers to rule out an irritant reaction and showed negative results. Finally, challenge tests conducted in our patient with another antifungal macrolide (parenteral amphotericin B) and antibiotic macrolides (oral clarithromycin, erythromycin, and azithromycin) were negative.

Patch and challenge test results along with the histologic findings led to diagnosis of concomitant systemic allergic contact dermatitis from oral nystatin.

Comment

Our patient presented with 2 unusual delayed hypersensitivity reactions that occurred in the same medical episode: allergic contact stomatitis from inhaled budesonide and systemic allergic contact dermatitis from oral nystatin. It is noteworthy that, despite the poor intestinal absorption of nystatin, systemic contact dermatitis to this drug has been previously described.³ Patch testing with macrolides proved useful for diagnosis in our patient, and based on the results we concluded that polyethylene glycol seemed to be the optimal vehicle for patch testing macrolide drugs versus water or petrolatum, as has been previously suggested.⁴

When a diagnosis of drug allergy is established, it is important to rule out cross-reactivity with other similar drugs by assessing if they produce the same reaction despite differences in chemical structure. Possible cross-reactivity of nystatin with other macrolides (validated on patch testing) has been reported but the tolerability was not evaluated.⁵ Our patient showed good tolerability to other macrolide drugs, both antibiotics and antifungals. Therefore, nystatin does not seem to cross-react with other structurally related drugs belonging to the macrolide group based on our results.

Corticosteroid allergies are more common than those associated with macrolides, especially contact dermatitis. Nonhalogenated corticosteroids (eg, hydrocortisone, budesonide) are most frequently associated with allergic reactions,⁶ and patch testing remains the diagnostic method of choice for the detection of delayed hypersensitivity to corticosteroids. In Europe, standard series include budesonide and tixocortol pivalate, and in the United States they include hydrocortisone 17–butyrate, triamcinolone acetonide, and clobetasol 17–propionate.⁶

To assess cross-reactivity among topical corticosteroids, patch testing with other steroids should be performed. In 1989, Coopman et al⁷ established a classification system for corticosteroids based on molecular structure, thus dividing them into 4 empirical groups: group A, hydrocortisone type; group B, acetonide type; group C, betamethasone type; and group D, ester type. The investigators hypothesized that allergic contact reactions occurred more frequently with corticosteroids belonging to the same group, while cross-reactions were uncommon between groups; however, cross-reactivity is known to occur among corticosteroids belonging to different groups in standard clinical practice, which conflicts with this claim.

Due to distinctively different behaviors among certain compounds in group D, Matura et al⁸ proposed subdividing the ester steroids into 2 groups: group D1, containing C16 methyl substitution and halogenation on the B ring, and group D2, comprising the labile ester steroids that lack both substitutions. A modified classification system including these subdivided groups is presented in the Table.⁸

In recent years, new corticosteroid drugs such as deflazacort, fluticasone propionate, and mometasone furoate have been developed, but classification of these agents has been difficult due to differences in their chemical structure, although mometasone furoate and fluticasone propionate have been included in group D1.⁹ Futhermore, the structural differences of these new steroids may mean less cross-reactivity with other steroids, which would facilitate their use in patients who are allergic to classic steroids. However, cross-reactivity between mometasone furoate and corticosteroids belonging to group B has already been described,¹⁰ which may restrict its use in patients who are allergic to other corticosteroids.

The classification of corticosteroids can provide useful information about cross-reactivity, which may help physicians in choosing an alternative drug in patients with an allergy to topical corticosteroids, but this advice about cross-reactivity does not seem to apply to systemic allergic dermatitis or immediate-type reactions to corticosteroids.¹¹ Therefore, in these types of reactions, an individualized evaluation of the sensitization profile is needed, performing wider studies with alternative corticosteroids by skin tests with late readings and challenge tests.

It is important to emphasize that hypersensitivity to corticosteroids should always be considered in the differential diagnosis along with oral candidiasis when oropharyngeal symptoms appear during inhaled corticosteroid along with oral candidiasis. We recommend that all drugs involved in a presumed allergic reaction must be systematically evaluated because an unexpected concomitant sensitization to multiple drugs could be present.

The development of concomitant allergic reactions to multiple drugs is uncommon. Dermatitis induced by topical or inhaled corticosteroids (eg, budesonide) is rare,¹ and allergic reactions associated with oral nystatin, a macrolide antifungal drug, also are unusual.² We present the case of concomitant sensitization to inhaled budesonide and oral nystatin presenting as allergic contact stomatitis and systemic allergic contact dermatitis. Concomitant allergic reactions to these treatments are rare and may result in diagnostic challenges for the physician.

Case Report

A 66-year-old woman presented to the Allergy Department for evaluation of painful erosions on the oral mucosa that had developed 72 hours after she started treatment with inhaled budesonide (400 mcg every 12 hours) prescribed by her general practitioner for a nonproductive cough. Budesonide inhalation was discontinued due to suspected oral candidiasis and treatment with oral nystatin (500,000 IU every 8 hours) was started, but the erosions did not resolve. After 2 days of treatment with oral nystatin, the patient presented with erythematous macules on the abdomen and thighs as well as a larger erythematous and edematous lesion with papules and vesicles on the hypothenar eminence of the right hand. Nystatin was discontinued and the lesions turned desquamative and healed spontaneously 7 days later. The oral lesions resolved after 15 days with no further treatment.

Patch testing was conducted using a commercially standard series of contact allergens, all of which showed negative results at 48 and 96 hours except for budesonide and triamcinolone, which led to the diagnosis of allergic contact stomatitis from the inhaled budesonide. Patch testing with other corticosteroids was negative. Challenge tests with alternative corticosteroids (ie, oral methylprednisolone, parenteral betamethasone, topical mometasone furoate, inhaled fluticasone) were negative.

In order to rule out involvement of oral nystatin, a single-blind, placebo-controlled oral challenge test was performed. Eight hours after taking oral nystatin (500,000 IU), erythematous macules developed on the patient’s abdomen along with an erythematous, 3×4-cm lesion with papules on the hypothenar eminence of the right hand that was similar in appearance to the original presentation. The lesion on the hand was biopsied and histologic examination revealed spongiosis, edema of the superficial dermis, perivascular lymphocytic infiltrates, and extravasated erythrocytes with no vasculitis. Further patch testing subsequently was conducted with antifungal and antibiotic macrolides in different vehicles (ie, petrolatum, water, polyethylene glycol), as well as with excipients of the oral nystatin formulation that had been tested (Figure). Patch testing was positive with nystatin 10% in petrolatum and nystatin 30,000 IU and 90,000 IU in polyethylene glycol. Testing also were conducted in 7 healthy volunteers to rule out an irritant reaction and showed negative results. Finally, challenge tests conducted in our patient with another antifungal macrolide (parenteral amphotericin B) and antibiotic macrolides (oral clarithromycin, erythromycin, and azithromycin) were negative.

Patch and challenge test results along with the histologic findings led to diagnosis of concomitant systemic allergic contact dermatitis from oral nystatin.

Comment

Our patient presented with 2 unusual delayed hypersensitivity reactions that occurred in the same medical episode: allergic contact stomatitis from inhaled budesonide and systemic allergic contact dermatitis from oral nystatin. It is noteworthy that, despite the poor intestinal absorption of nystatin, systemic contact dermatitis to this drug has been previously described.³ Patch testing with macrolides proved useful for diagnosis in our patient, and based on the results we concluded that polyethylene glycol seemed to be the optimal vehicle for patch testing macrolide drugs versus water or petrolatum, as has been previously suggested.⁴

When a diagnosis of drug allergy is established, it is important to rule out cross-reactivity with other similar drugs by assessing if they produce the same reaction despite differences in chemical structure. Possible cross-reactivity of nystatin with other macrolides (validated on patch testing) has been reported but the tolerability was not evaluated.⁵ Our patient showed good tolerability to other macrolide drugs, both antibiotics and antifungals. Therefore, nystatin does not seem to cross-react with other structurally related drugs belonging to the macrolide group based on our results.

Corticosteroid allergies are more common than those associated with macrolides, especially contact dermatitis. Nonhalogenated corticosteroids (eg, hydrocortisone, budesonide) are most frequently associated with allergic reactions,⁶ and patch testing remains the diagnostic method of choice for the detection of delayed hypersensitivity to corticosteroids. In Europe, standard series include budesonide and tixocortol pivalate, and in the United States they include hydrocortisone 17–butyrate, triamcinolone acetonide, and clobetasol 17–propionate.⁶

To assess cross-reactivity among topical corticosteroids, patch testing with other steroids should be performed. In 1989, Coopman et al⁷ established a classification system for corticosteroids based on molecular structure, thus dividing them into 4 empirical groups: group A, hydrocortisone type; group B, acetonide type; group C, betamethasone type; and group D, ester type. The investigators hypothesized that allergic contact reactions occurred more frequently with corticosteroids belonging to the same group, while cross-reactions were uncommon between groups; however, cross-reactivity is known to occur among corticosteroids belonging to different groups in standard clinical practice, which conflicts with this claim.

Due to distinctively different behaviors among certain compounds in group D, Matura et al⁸ proposed subdividing the ester steroids into 2 groups: group D1, containing C16 methyl substitution and halogenation on the B ring, and group D2, comprising the labile ester steroids that lack both substitutions. A modified classification system including these subdivided groups is presented in the Table.⁸

In recent years, new corticosteroid drugs such as deflazacort, fluticasone propionate, and mometasone furoate have been developed, but classification of these agents has been difficult due to differences in their chemical structure, although mometasone furoate and fluticasone propionate have been included in group D1.⁹ Futhermore, the structural differences of these new steroids may mean less cross-reactivity with other steroids, which would facilitate their use in patients who are allergic to classic steroids. However, cross-reactivity between mometasone furoate and corticosteroids belonging to group B has already been described,¹⁰ which may restrict its use in patients who are allergic to other corticosteroids.

The classification of corticosteroids can provide useful information about cross-reactivity, which may help physicians in choosing an alternative drug in patients with an allergy to topical corticosteroids, but this advice about cross-reactivity does not seem to apply to systemic allergic dermatitis or immediate-type reactions to corticosteroids.¹¹ Therefore, in these types of reactions, an individualized evaluation of the sensitization profile is needed, performing wider studies with alternative corticosteroids by skin tests with late readings and challenge tests.

It is important to emphasize that hypersensitivity to corticosteroids should always be considered in the differential diagnosis along with oral candidiasis when oropharyngeal symptoms appear during inhaled corticosteroid along with oral candidiasis. We recommend that all drugs involved in a presumed allergic reaction must be systematically evaluated because an unexpected concomitant sensitization to multiple drugs could be present.

Latex allergy is an all-encompassing term used to describe hypersensitivity reactions to products containing natural rubber latex from the Hevea brasiliensis tree and affects approximately 1% to 2% of the general population.¹ Although latex gloves are the most widely known culprits, several other commonly used products can contain natural rubber latex, including adhesive tape, balloons, condoms, rubber bands, paint, tourniquets, electrode pads, and Foley catheters.² The term latex allergy often is used as a general diagnosis, but there are in fact 3 distinct mechanisms by which individuals may develop an adverse reaction to latex-containing products: irritant contact dermatitis, allergic contact dermatitis (type IV hypersensitivity) and true latex allergy (type I hypersensitivity).

Irritant Contact Dermatitis

Irritant contact dermatitis, a nonimmunologic reaction, occurs due to mechanical factors (eg, friction) or contact with chemicals, which can have irritating and dehydrating effects. Individuals with irritant contact dermatitis do not have true latex allergy and will not necessarily develop a reaction to products containing natural rubber latex. Incorrectly attributing these irritant contact dermatitis reactions to latex allergy and simply advising patients to avoid all latex products (eg, use nitrile gloves rather than latex gloves) will not address the underlying problem. Rather, these patients must be informed that the dermatitis is a result of a disruption to the natural, protective skin barrier and not an allergic reaction.

Allergic Contact Dermatitis

Allergic contact dermatitis to rubber is caused by a type IV (delayed) hypersensitivity reaction and is the result of exposure to the accelerators present in rubber products in sensitive individuals. Individuals experiencing this type of reaction typically develop localized erythema, pruritus, and urticarial lesions 48 hours after exposure.³ Incorrectly labeling this problem as latex allergy and recommending nonlatex rubber substitutes (eg, hypoallergenic gloves) likely will not be effective, as these nonlatex replacement products contain the same accelerators as do latex gloves.

True Latex Allergy

The most severe form of latex allergy, often referred to as true latex allergy, is caused by a type I (immediate) hypersensitivity reaction mediated by immunoglobulin E (IgE) antibodies. Individuals experiencing this type of reaction have a systemic response to latex proteins that may result in fulminant anaphylaxis. Individuals with true latex allergy must absolutely avoid latex products, and substituting nonlatex products is the most effective approach.

Latex Reactions in Medical Practice

The varying propensity of certain populations to develop latex allergy has been well documented; for example, the prevalence of hypersensitivity in patients with spina bifida ranges from 20% to 65%, figures that are much higher than those reported in the general population.³ This hypersensitivity in patients with spina bifida most likely results from repeated exposure to latex products during corrective surgeries and diagnostic procedures early in life. Atopic individuals, such as those with allergic rhinitis, eczema, and asthma, have a 4-fold increased risk for developing latex allergy compared to nonatopic individuals.⁴ The risk of latex allergy among health care workers is increased due to increased exposure to rubber products. One study found that the risk of latex sensitization among health care workers exposed to products containing latex was 4.3%, while the risk in the general population was only 1.37%.¹ Those at highest risk for sensitization include dental assistants, operating room personnel, hospital housekeeping staff, and paramedics or emergency medical technicians.³ However, sensitization documented on laboratory assessment does not reliably correlate with symptomatic allergy, as many patients with a positive IgE test do not show clinical symptoms. Schmid et al⁴ demonstrated that a 1.3% prevalence of clinically symptomatic latex allergy among health care workers may approximate the prevalence of latex allergy in the general population. In a study by Brown et al,⁵ although 12.5% of anesthesiologists were found to be sensitized to latex, only 2.4% had clinically symptomatic allergic reactions.

Testing for Latex Allergy

Several diagnostic tests are available to establish a diagnosis of type I sensitization or true latex allergy. Skin prick testing is an in vivo assay and is the gold standard for diagnosing IgE-mediated type I hypersensitivity to latex. The test involves pricking the skin of the forearm and applying a commercial extract of nonammoniated latex to monitor for development of a wheal within several minutes. The skin prick test should be performed in a health care setting equipped with oxygen, epinephrine, and latex-free resuscitation equipment in case of anaphylaxis following exposure. Although latex skin prick testing is the gold standard, it is rarely performed in the United States because there is no US Food and Drug Administration–approved natural rubber latex reagent.³ Consequently, physicians who wish to perform skin prick testing for latex allergy are forced to develop improvised reagents from the H brasiliensis tree itself or from highly allergenic latex gloves. Standardized latex allergens are commercially available in Europe.

The most noninvasive method of latex allergy testing is an in vitro assay for latex-specific IgE antibodies, which can be detected by either a radioallergosorbent test (RAST) or enzyme-linked immunosorbent assay (ELISA). The presence of antilatex IgE antibodies confirms sensitization but does not necessarily mean the patient will develop a symptomatic reaction following exposure. Due to the unavailability of a standardized reagent for the skin prick test in the United States, evaluation of latex-specific serum IgE levels may be the best alternative. While the skin prick test has the highest sensitivity, the sensitivity and specificity of latex-specific serum IgE testing are 50% to 90% and 80% to 87%, respectively.⁶

The wear test (also known as the use or glove provocation test), can be used to diagnose clinically symptomatic latex allergy when there is a discrepancy between the patient’s clinical history and results from skin prick or serum IgE antibody testing. To perform the wear test, place a natural rubber latex glove on one of the patient’s fingers for 15 minutes and monitor the area for development of urticaria. If there is no evidence of allergic reaction within 15 minutes, place the glove on the whole hand for an additional 15 minutes. The patient is said to be nonreactive if a latex glove can be placed on the entire hand for 15 minutes without evidence of reaction.³

Lastly, patch testing can differentiate between irritant contact and allergic contact (type IV hypersensitivity) dermatitis. Apply a small amount of each substance of interest onto a separate disc and place the discs in direct contact with the skin using hypoallergenic tape. With type IV latex hypersensitivity, the skin underneath the disc will become erythematous with developing papulovesicles, starting between 2 and 5 days after exposure. The Figure outlines the differentiation of true latex allergy from irritant and allergic contact dermatitis and identifies methods for making these diagnoses.

General Medical Protocol With Latex Reactions

To reduce the incidence of latex allergic reactions among health care workers and patients, Kumar² recommends putting a protocol in place to document steps in preventing, diagnosing, and treating latex allergy. This protocol includes employee and patient education about the risks for developing latex allergy and the signs and symptoms of a reaction; available diagnostic testing; and alternative products (eg, hypoallergenic gloves) that are available to individuals with a known or suspected allergy. At-risk health care workers who have not been sensitized should be advised to avoid latex-containing products.³ Routine questioning and diagnostic testing may be necessary as part of every preoperative assessment, as there have been reported cases of anaphylaxis in patients with undocumented allergies.⁷ Anaphylaxis caused by latex allergy is the second leading cause of perioperative anaphylaxis, accounting for as many as 20% of cases.⁸ With the use of preventative measures and early identification of at-risk patients, the incidence of latex-related anaphylaxis is decreasing.⁸ Ascertaining valuable information about the patient’s medical history, such as known allergies to foods that have cross-reactivity to latex (eg, bananas, mango, kiwi, avocado), is one simple way of identifying a patient who should be tested for possible underlying latex allergy.⁸ Total avoidance of latex-containing products (eg, in the workplace) can further reduce the incidence of allergic reactions by decreasing primary sensitization and risk of exposure.

Conclusion

Patients claiming to be allergic to latex without documentation should be tested. The diagnostic testing available in the United States includes patch testing, wear (or glove provocation) testing, or assessment of IgE antibody titer. Accurate differentiation among irritant contact dermatitis, allergic contact dermatitis, and true latex allergy is paramount for properly educating patients and effectively treating these conditions. Additionally, distinguishing patients with true latex allergy from those who have been misdiagnosed can save resources and reduce health care costs.

Latex allergy is an all-encompassing term used to describe hypersensitivity reactions to products containing natural rubber latex from the Hevea brasiliensis tree and affects approximately 1% to 2% of the general population.¹ Although latex gloves are the most widely known culprits, several other commonly used products can contain natural rubber latex, including adhesive tape, balloons, condoms, rubber bands, paint, tourniquets, electrode pads, and Foley catheters.² The term latex allergy often is used as a general diagnosis, but there are in fact 3 distinct mechanisms by which individuals may develop an adverse reaction to latex-containing products: irritant contact dermatitis, allergic contact dermatitis (type IV hypersensitivity) and true latex allergy (type I hypersensitivity).

Irritant Contact Dermatitis

Irritant contact dermatitis, a nonimmunologic reaction, occurs due to mechanical factors (eg, friction) or contact with chemicals, which can have irritating and dehydrating effects. Individuals with irritant contact dermatitis do not have true latex allergy and will not necessarily develop a reaction to products containing natural rubber latex. Incorrectly attributing these irritant contact dermatitis reactions to latex allergy and simply advising patients to avoid all latex products (eg, use nitrile gloves rather than latex gloves) will not address the underlying problem. Rather, these patients must be informed that the dermatitis is a result of a disruption to the natural, protective skin barrier and not an allergic reaction.

Allergic Contact Dermatitis

Allergic contact dermatitis to rubber is caused by a type IV (delayed) hypersensitivity reaction and is the result of exposure to the accelerators present in rubber products in sensitive individuals. Individuals experiencing this type of reaction typically develop localized erythema, pruritus, and urticarial lesions 48 hours after exposure.³ Incorrectly labeling this problem as latex allergy and recommending nonlatex rubber substitutes (eg, hypoallergenic gloves) likely will not be effective, as these nonlatex replacement products contain the same accelerators as do latex gloves.

True Latex Allergy

The most severe form of latex allergy, often referred to as true latex allergy, is caused by a type I (immediate) hypersensitivity reaction mediated by immunoglobulin E (IgE) antibodies. Individuals experiencing this type of reaction have a systemic response to latex proteins that may result in fulminant anaphylaxis. Individuals with true latex allergy must absolutely avoid latex products, and substituting nonlatex products is the most effective approach.

Latex Reactions in Medical Practice

The varying propensity of certain populations to develop latex allergy has been well documented; for example, the prevalence of hypersensitivity in patients with spina bifida ranges from 20% to 65%, figures that are much higher than those reported in the general population.³ This hypersensitivity in patients with spina bifida most likely results from repeated exposure to latex products during corrective surgeries and diagnostic procedures early in life. Atopic individuals, such as those with allergic rhinitis, eczema, and asthma, have a 4-fold increased risk for developing latex allergy compared to nonatopic individuals.⁴ The risk of latex allergy among health care workers is increased due to increased exposure to rubber products. One study found that the risk of latex sensitization among health care workers exposed to products containing latex was 4.3%, while the risk in the general population was only 1.37%.¹ Those at highest risk for sensitization include dental assistants, operating room personnel, hospital housekeeping staff, and paramedics or emergency medical technicians.³ However, sensitization documented on laboratory assessment does not reliably correlate with symptomatic allergy, as many patients with a positive IgE test do not show clinical symptoms. Schmid et al⁴ demonstrated that a 1.3% prevalence of clinically symptomatic latex allergy among health care workers may approximate the prevalence of latex allergy in the general population. In a study by Brown et al,⁵ although 12.5% of anesthesiologists were found to be sensitized to latex, only 2.4% had clinically symptomatic allergic reactions.

Testing for Latex Allergy

Several diagnostic tests are available to establish a diagnosis of type I sensitization or true latex allergy. Skin prick testing is an in vivo assay and is the gold standard for diagnosing IgE-mediated type I hypersensitivity to latex. The test involves pricking the skin of the forearm and applying a commercial extract of nonammoniated latex to monitor for development of a wheal within several minutes. The skin prick test should be performed in a health care setting equipped with oxygen, epinephrine, and latex-free resuscitation equipment in case of anaphylaxis following exposure. Although latex skin prick testing is the gold standard, it is rarely performed in the United States because there is no US Food and Drug Administration–approved natural rubber latex reagent.³ Consequently, physicians who wish to perform skin prick testing for latex allergy are forced to develop improvised reagents from the H brasiliensis tree itself or from highly allergenic latex gloves. Standardized latex allergens are commercially available in Europe.

The most noninvasive method of latex allergy testing is an in vitro assay for latex-specific IgE antibodies, which can be detected by either a radioallergosorbent test (RAST) or enzyme-linked immunosorbent assay (ELISA). The presence of antilatex IgE antibodies confirms sensitization but does not necessarily mean the patient will develop a symptomatic reaction following exposure. Due to the unavailability of a standardized reagent for the skin prick test in the United States, evaluation of latex-specific serum IgE levels may be the best alternative. While the skin prick test has the highest sensitivity, the sensitivity and specificity of latex-specific serum IgE testing are 50% to 90% and 80% to 87%, respectively.⁶

The wear test (also known as the use or glove provocation test), can be used to diagnose clinically symptomatic latex allergy when there is a discrepancy between the patient’s clinical history and results from skin prick or serum IgE antibody testing. To perform the wear test, place a natural rubber latex glove on one of the patient’s fingers for 15 minutes and monitor the area for development of urticaria. If there is no evidence of allergic reaction within 15 minutes, place the glove on the whole hand for an additional 15 minutes. The patient is said to be nonreactive if a latex glove can be placed on the entire hand for 15 minutes without evidence of reaction.³

Lastly, patch testing can differentiate between irritant contact and allergic contact (type IV hypersensitivity) dermatitis. Apply a small amount of each substance of interest onto a separate disc and place the discs in direct contact with the skin using hypoallergenic tape. With type IV latex hypersensitivity, the skin underneath the disc will become erythematous with developing papulovesicles, starting between 2 and 5 days after exposure. The Figure outlines the differentiation of true latex allergy from irritant and allergic contact dermatitis and identifies methods for making these diagnoses.

General Medical Protocol With Latex Reactions

To reduce the incidence of latex allergic reactions among health care workers and patients, Kumar² recommends putting a protocol in place to document steps in preventing, diagnosing, and treating latex allergy. This protocol includes employee and patient education about the risks for developing latex allergy and the signs and symptoms of a reaction; available diagnostic testing; and alternative products (eg, hypoallergenic gloves) that are available to individuals with a known or suspected allergy. At-risk health care workers who have not been sensitized should be advised to avoid latex-containing products.³ Routine questioning and diagnostic testing may be necessary as part of every preoperative assessment, as there have been reported cases of anaphylaxis in patients with undocumented allergies.⁷ Anaphylaxis caused by latex allergy is the second leading cause of perioperative anaphylaxis, accounting for as many as 20% of cases.⁸ With the use of preventative measures and early identification of at-risk patients, the incidence of latex-related anaphylaxis is decreasing.⁸ Ascertaining valuable information about the patient’s medical history, such as known allergies to foods that have cross-reactivity to latex (eg, bananas, mango, kiwi, avocado), is one simple way of identifying a patient who should be tested for possible underlying latex allergy.⁸ Total avoidance of latex-containing products (eg, in the workplace) can further reduce the incidence of allergic reactions by decreasing primary sensitization and risk of exposure.

Conclusion

Patients claiming to be allergic to latex without documentation should be tested. The diagnostic testing available in the United States includes patch testing, wear (or glove provocation) testing, or assessment of IgE antibody titer. Accurate differentiation among irritant contact dermatitis, allergic contact dermatitis, and true latex allergy is paramount for properly educating patients and effectively treating these conditions. Additionally, distinguishing patients with true latex allergy from those who have been misdiagnosed can save resources and reduce health care costs.

Latex allergy is an all-encompassing term used to describe hypersensitivity reactions to products containing natural rubber latex from the Hevea brasiliensis tree and affects approximately 1% to 2% of the general population.¹ Although latex gloves are the most widely known culprits, several other commonly used products can contain natural rubber latex, including adhesive tape, balloons, condoms, rubber bands, paint, tourniquets, electrode pads, and Foley catheters.² The term latex allergy often is used as a general diagnosis, but there are in fact 3 distinct mechanisms by which individuals may develop an adverse reaction to latex-containing products: irritant contact dermatitis, allergic contact dermatitis (type IV hypersensitivity) and true latex allergy (type I hypersensitivity).

Irritant Contact Dermatitis

Irritant contact dermatitis, a nonimmunologic reaction, occurs due to mechanical factors (eg, friction) or contact with chemicals, which can have irritating and dehydrating effects. Individuals with irritant contact dermatitis do not have true latex allergy and will not necessarily develop a reaction to products containing natural rubber latex. Incorrectly attributing these irritant contact dermatitis reactions to latex allergy and simply advising patients to avoid all latex products (eg, use nitrile gloves rather than latex gloves) will not address the underlying problem. Rather, these patients must be informed that the dermatitis is a result of a disruption to the natural, protective skin barrier and not an allergic reaction.

Allergic Contact Dermatitis

Allergic contact dermatitis to rubber is caused by a type IV (delayed) hypersensitivity reaction and is the result of exposure to the accelerators present in rubber products in sensitive individuals. Individuals experiencing this type of reaction typically develop localized erythema, pruritus, and urticarial lesions 48 hours after exposure.³ Incorrectly labeling this problem as latex allergy and recommending nonlatex rubber substitutes (eg, hypoallergenic gloves) likely will not be effective, as these nonlatex replacement products contain the same accelerators as do latex gloves.

True Latex Allergy

The most severe form of latex allergy, often referred to as true latex allergy, is caused by a type I (immediate) hypersensitivity reaction mediated by immunoglobulin E (IgE) antibodies. Individuals experiencing this type of reaction have a systemic response to latex proteins that may result in fulminant anaphylaxis. Individuals with true latex allergy must absolutely avoid latex products, and substituting nonlatex products is the most effective approach.

Latex Reactions in Medical Practice

The varying propensity of certain populations to develop latex allergy has been well documented; for example, the prevalence of hypersensitivity in patients with spina bifida ranges from 20% to 65%, figures that are much higher than those reported in the general population.³ This hypersensitivity in patients with spina bifida most likely results from repeated exposure to latex products during corrective surgeries and diagnostic procedures early in life. Atopic individuals, such as those with allergic rhinitis, eczema, and asthma, have a 4-fold increased risk for developing latex allergy compared to nonatopic individuals.⁴ The risk of latex allergy among health care workers is increased due to increased exposure to rubber products. One study found that the risk of latex sensitization among health care workers exposed to products containing latex was 4.3%, while the risk in the general population was only 1.37%.¹ Those at highest risk for sensitization include dental assistants, operating room personnel, hospital housekeeping staff, and paramedics or emergency medical technicians.³ However, sensitization documented on laboratory assessment does not reliably correlate with symptomatic allergy, as many patients with a positive IgE test do not show clinical symptoms. Schmid et al⁴ demonstrated that a 1.3% prevalence of clinically symptomatic latex allergy among health care workers may approximate the prevalence of latex allergy in the general population. In a study by Brown et al,⁵ although 12.5% of anesthesiologists were found to be sensitized to latex, only 2.4% had clinically symptomatic allergic reactions.

Testing for Latex Allergy

Several diagnostic tests are available to establish a diagnosis of type I sensitization or true latex allergy. Skin prick testing is an in vivo assay and is the gold standard for diagnosing IgE-mediated type I hypersensitivity to latex. The test involves pricking the skin of the forearm and applying a commercial extract of nonammoniated latex to monitor for development of a wheal within several minutes. The skin prick test should be performed in a health care setting equipped with oxygen, epinephrine, and latex-free resuscitation equipment in case of anaphylaxis following exposure. Although latex skin prick testing is the gold standard, it is rarely performed in the United States because there is no US Food and Drug Administration–approved natural rubber latex reagent.³ Consequently, physicians who wish to perform skin prick testing for latex allergy are forced to develop improvised reagents from the H brasiliensis tree itself or from highly allergenic latex gloves. Standardized latex allergens are commercially available in Europe.

The most noninvasive method of latex allergy testing is an in vitro assay for latex-specific IgE antibodies, which can be detected by either a radioallergosorbent test (RAST) or enzyme-linked immunosorbent assay (ELISA). The presence of antilatex IgE antibodies confirms sensitization but does not necessarily mean the patient will develop a symptomatic reaction following exposure. Due to the unavailability of a standardized reagent for the skin prick test in the United States, evaluation of latex-specific serum IgE levels may be the best alternative. While the skin prick test has the highest sensitivity, the sensitivity and specificity of latex-specific serum IgE testing are 50% to 90% and 80% to 87%, respectively.⁶

The wear test (also known as the use or glove provocation test), can be used to diagnose clinically symptomatic latex allergy when there is a discrepancy between the patient’s clinical history and results from skin prick or serum IgE antibody testing. To perform the wear test, place a natural rubber latex glove on one of the patient’s fingers for 15 minutes and monitor the area for development of urticaria. If there is no evidence of allergic reaction within 15 minutes, place the glove on the whole hand for an additional 15 minutes. The patient is said to be nonreactive if a latex glove can be placed on the entire hand for 15 minutes without evidence of reaction.³

Lastly, patch testing can differentiate between irritant contact and allergic contact (type IV hypersensitivity) dermatitis. Apply a small amount of each substance of interest onto a separate disc and place the discs in direct contact with the skin using hypoallergenic tape. With type IV latex hypersensitivity, the skin underneath the disc will become erythematous with developing papulovesicles, starting between 2 and 5 days after exposure. The Figure outlines the differentiation of true latex allergy from irritant and allergic contact dermatitis and identifies methods for making these diagnoses.

General Medical Protocol With Latex Reactions

To reduce the incidence of latex allergic reactions among health care workers and patients, Kumar² recommends putting a protocol in place to document steps in preventing, diagnosing, and treating latex allergy. This protocol includes employee and patient education about the risks for developing latex allergy and the signs and symptoms of a reaction; available diagnostic testing; and alternative products (eg, hypoallergenic gloves) that are available to individuals with a known or suspected allergy. At-risk health care workers who have not been sensitized should be advised to avoid latex-containing products.³ Routine questioning and diagnostic testing may be necessary as part of every preoperative assessment, as there have been reported cases of anaphylaxis in patients with undocumented allergies.⁷ Anaphylaxis caused by latex allergy is the second leading cause of perioperative anaphylaxis, accounting for as many as 20% of cases.⁸ With the use of preventative measures and early identification of at-risk patients, the incidence of latex-related anaphylaxis is decreasing.⁸ Ascertaining valuable information about the patient’s medical history, such as known allergies to foods that have cross-reactivity to latex (eg, bananas, mango, kiwi, avocado), is one simple way of identifying a patient who should be tested for possible underlying latex allergy.⁸ Total avoidance of latex-containing products (eg, in the workplace) can further reduce the incidence of allergic reactions by decreasing primary sensitization and risk of exposure.

Conclusion

Patients claiming to be allergic to latex without documentation should be tested. The diagnostic testing available in the United States includes patch testing, wear (or glove provocation) testing, or assessment of IgE antibody titer. Accurate differentiation among irritant contact dermatitis, allergic contact dermatitis, and true latex allergy is paramount for properly educating patients and effectively treating these conditions. Additionally, distinguishing patients with true latex allergy from those who have been misdiagnosed can save resources and reduce health care costs.

Atopic dermatitis (AD) is a multifactorial inflammatory disorder with an estimated prevalence of 279,889,120 cases worldwide.1 Most cases of AD begin in early childhood (with almost 85% developing by 5 years of age),² but recent studies have found that 40% to over 80% of cases persist into adulthood.^1,3,4 Although a previous study focused largely on T helper type 1/T helper type 2 (Th2) immune dysregulation as the pathogenesis of the disease,⁵ disruption of the skin barrier and systemic inflammation are at the center of current AD research. In AD, breakdown of the skin barrier results in increased transepidermal water loss, reduced skin hydration, and increased antigen presentation by Langerhans cells initiating inflammation.6-8 The cascade largely activated is the Th2 and T helper type 22 cascade with resultant cytokine release (ie, IL-4, IL-13, IL-2, IL-8, IL-10, IL-17, IL-22, tumor necrosis factor α, interferon γ).^9,10 In active AD, Th2 inflammation and barrier breakdown result in reduced filaggrin and claudin 1 expression, resulting in further exacerbation of the barrier defect and enhancing the risk of development of asthma and hay fever as well as transcutaneous sensitization to a variety of food allergens (eg, peanuts).^9,11,12 Although all of these immunologic features are well established in AD, controversy remains as to whether AD is caused by systemic inflammation triggering barrier dysfunction (the “inside-out” hypothesis) or from the epidermal skin barrier disruption triggering immunologic imbalance (the “outside-in” hypothesis).

Inside-Out Hypothesis

While barrier impairment appears to occur in all patients with AD, it still is unclear how AD begins. The inside-out hypothesis suggests that cutaneous inflammation precedes barrier impairment and in fact may result in an impaired skin barrier. It has previously been reported that inflammatory states weaken the barrier by downregulating filaggrin production in the skin.¹³ Barrier disruption may be accompanied by transcutaneous penetration of allergens and increased Staphylococcus aureus counts. Recently, mutations and polymorphisms of inflammatory genes have been linked to AD (eg, single nucleotide polymorphisms of the IL4RA [interleukin 4 receptor, alpha] and CD14 [cluster of differentiation 14] genes, the serine protease inhibitor SPINK5 [serine peptidase inhibitor, Kazal type 5], RANTES [chemokine (C-C motif) ligand 5], IL-4, IL-13).¹⁴ These alterations highlight the role of systemic inflammation in triggering AD.

Outside-In Hypothesis

The outside-in hypothesis suggests that the impaired skin barrier precedes AD and is required for immune dysregulation to occur. This hypothesis was largely advanced by a study demonstrating that deactivating mutations of the filaggrin gene were linked to nearly 20% of AD cases in Northern European populations.15 Filaggrin (chromosome 1q21.3) performs an essential function in the skin barrier through its differential cleavage and the breakdown and release of natural moisturizing factor.¹⁶ Filaggrin gene mutations are associated with persistent AD, and it has been posited that environmental factors such as temperature and humidity also can affect filaggrin production as it relates to barrier function.17-19 Skin barrier disruption results in increased cutaneous and systemic Th2 responses (ie, IL-4/13), with thymic stromal lymphopoietin as the potential mechanism of Th2 cell recruitment.^10,20 Inflammatory Th2 cells triggered by an impaired skin barrier also may predispose patients to the development of allergic diseases such as asthma, in line with Atopic March, or the progression of AD to other forms of atopy (eg, food allergy, asthma).^5,7,21-23

The outside-in hypothesis may only explain the root pathogenesis of AD in a subset of patients, however, as only 1 in 5 cases of AD in Northern European and Asian populations are associated with underlying filaggrin mutations (which are only present in about 10% of those who are unaffected by AD).¹⁵ Filaggrin does not appear to account for the basis of AD in all cases. In a study of 762 newborns in Cincinnati, Ohio, 39% of children with at least one parent with atopy developed AD by 3 years of age, about quadruple of what would be projected based on filaggrin defects in general population studies, which are noted in only about 10% of white individuals.²⁴ Furthermore, less than 5% of patients of African descent have mutations of the filaggrin 1 gene.²⁵

Implications for the Prevention and Treatment of Atopic Dermatitis

Preventative strategies for AD currently are in development. Atopic dermatitis may be unpreventable because the in utero environment triggers some of the barrier alterations, which can be noted as early as 2 days following birth and will predict early-onset AD. The putative mechanism is via Th2 cytokines (IL-4, IL-13).²⁶

Certainly, application of over-the-counter and prescription emollients are mainstays of treatment for AD and may suffice as monotherapy in cases of mild disease. In a recent randomized trial in the United States and the United Kingdom, emollients were used in newborns considered at high risk for AD (family history of atopy) until 6 months of age.²⁷ The risk of AD development was reduced by half, irrespective of the emollient used. Unfortunately, 21.8% of children without a family history of atopy will develop AD; therefore, not all cases can be prevented if use of emollients is limited to newborns with a family history of atopy.²⁸ Long-term follow-up is needed to track whether emollient use in newborns will prevent AD indefinitely.

Prevention of AD onset using systemic interventions has also been investigated. Probiotics have been suggested as a means to modify the gut microbiota and reduce systemic and mucosal inflammation. Lactobacillus reuteri taken prenatally by pregnant women and by newborns has shown mild benefit in preventing some forms of AD.29 Although they are not approved by the US Food and Drug Administration for this indication, systemic interventions for moderate-to-severe AD such as methotrexate and cyclosporine certainly have shown benefit in managing ongoing illness and breaking the cycle of disease.³⁰ The efficacy of these agents points to the role of systemic inflammation in ongoing AD activity. Moreover, the inside-out hypothesis recently has led to the proliferation of promising new therapeutic agents in the pipeline to treat the systemic Th2 inflammation that occurs in severe AD (eg, anti–IL-4/13 receptor antibody, anti–IL-13 antibodies, and biologics targeting IL-12/23, IL-22, and IL-31 receptors).³¹

Final Thoughts

Atopic dermatitis is a multifactorial disease associated with barrier disruption and intense systemic inflammation. It is likely that both the inside-out and outside-in hypotheses hold true in different subsets of AD patients. It is clear that some individuals are born with filaggrin defects that sufficiently trigger systemic inflammation, resulting in AD. On the other hand, there are clearly some individuals with inflammatory dysregulation that results in systemic inflammation and secondary barrier disruption. Until we can determine the genomic triggering or promoting event in each individual patient, large-scale introduction of active prevention and severity reduction strategies may not be realistic. In the meantime, we can approach AD in childhood from the inside out, through appropriate treatment of systemic inflammation of AD, and from the outside in, with treatment and prevention via emollient use in newborns.

Atopic dermatitis (AD) is a multifactorial inflammatory disorder with an estimated prevalence of 279,889,120 cases worldwide.1 Most cases of AD begin in early childhood (with almost 85% developing by 5 years of age),² but recent studies have found that 40% to over 80% of cases persist into adulthood.^1,3,4 Although a previous study focused largely on T helper type 1/T helper type 2 (Th2) immune dysregulation as the pathogenesis of the disease,⁵ disruption of the skin barrier and systemic inflammation are at the center of current AD research. In AD, breakdown of the skin barrier results in increased transepidermal water loss, reduced skin hydration, and increased antigen presentation by Langerhans cells initiating inflammation.6-8 The cascade largely activated is the Th2 and T helper type 22 cascade with resultant cytokine release (ie, IL-4, IL-13, IL-2, IL-8, IL-10, IL-17, IL-22, tumor necrosis factor α, interferon γ).^9,10 In active AD, Th2 inflammation and barrier breakdown result in reduced filaggrin and claudin 1 expression, resulting in further exacerbation of the barrier defect and enhancing the risk of development of asthma and hay fever as well as transcutaneous sensitization to a variety of food allergens (eg, peanuts).^9,11,12 Although all of these immunologic features are well established in AD, controversy remains as to whether AD is caused by systemic inflammation triggering barrier dysfunction (the “inside-out” hypothesis) or from the epidermal skin barrier disruption triggering immunologic imbalance (the “outside-in” hypothesis).

Inside-Out Hypothesis

While barrier impairment appears to occur in all patients with AD, it still is unclear how AD begins. The inside-out hypothesis suggests that cutaneous inflammation precedes barrier impairment and in fact may result in an impaired skin barrier. It has previously been reported that inflammatory states weaken the barrier by downregulating filaggrin production in the skin.¹³ Barrier disruption may be accompanied by transcutaneous penetration of allergens and increased Staphylococcus aureus counts. Recently, mutations and polymorphisms of inflammatory genes have been linked to AD (eg, single nucleotide polymorphisms of the IL4RA [interleukin 4 receptor, alpha] and CD14 [cluster of differentiation 14] genes, the serine protease inhibitor SPINK5 [serine peptidase inhibitor, Kazal type 5], RANTES [chemokine (C-C motif) ligand 5], IL-4, IL-13).¹⁴ These alterations highlight the role of systemic inflammation in triggering AD.

Outside-In Hypothesis

The outside-in hypothesis suggests that the impaired skin barrier precedes AD and is required for immune dysregulation to occur. This hypothesis was largely advanced by a study demonstrating that deactivating mutations of the filaggrin gene were linked to nearly 20% of AD cases in Northern European populations.15 Filaggrin (chromosome 1q21.3) performs an essential function in the skin barrier through its differential cleavage and the breakdown and release of natural moisturizing factor.¹⁶ Filaggrin gene mutations are associated with persistent AD, and it has been posited that environmental factors such as temperature and humidity also can affect filaggrin production as it relates to barrier function.17-19 Skin barrier disruption results in increased cutaneous and systemic Th2 responses (ie, IL-4/13), with thymic stromal lymphopoietin as the potential mechanism of Th2 cell recruitment.^10,20 Inflammatory Th2 cells triggered by an impaired skin barrier also may predispose patients to the development of allergic diseases such as asthma, in line with Atopic March, or the progression of AD to other forms of atopy (eg, food allergy, asthma).^5,7,21-23

The outside-in hypothesis may only explain the root pathogenesis of AD in a subset of patients, however, as only 1 in 5 cases of AD in Northern European and Asian populations are associated with underlying filaggrin mutations (which are only present in about 10% of those who are unaffected by AD).¹⁵ Filaggrin does not appear to account for the basis of AD in all cases. In a study of 762 newborns in Cincinnati, Ohio, 39% of children with at least one parent with atopy developed AD by 3 years of age, about quadruple of what would be projected based on filaggrin defects in general population studies, which are noted in only about 10% of white individuals.²⁴ Furthermore, less than 5% of patients of African descent have mutations of the filaggrin 1 gene.²⁵

Implications for the Prevention and Treatment of Atopic Dermatitis

Preventative strategies for AD currently are in development. Atopic dermatitis may be unpreventable because the in utero environment triggers some of the barrier alterations, which can be noted as early as 2 days following birth and will predict early-onset AD. The putative mechanism is via Th2 cytokines (IL-4, IL-13).²⁶

Certainly, application of over-the-counter and prescription emollients are mainstays of treatment for AD and may suffice as monotherapy in cases of mild disease. In a recent randomized trial in the United States and the United Kingdom, emollients were used in newborns considered at high risk for AD (family history of atopy) until 6 months of age.²⁷ The risk of AD development was reduced by half, irrespective of the emollient used. Unfortunately, 21.8% of children without a family history of atopy will develop AD; therefore, not all cases can be prevented if use of emollients is limited to newborns with a family history of atopy.²⁸ Long-term follow-up is needed to track whether emollient use in newborns will prevent AD indefinitely.

Prevention of AD onset using systemic interventions has also been investigated. Probiotics have been suggested as a means to modify the gut microbiota and reduce systemic and mucosal inflammation. Lactobacillus reuteri taken prenatally by pregnant women and by newborns has shown mild benefit in preventing some forms of AD.29 Although they are not approved by the US Food and Drug Administration for this indication, systemic interventions for moderate-to-severe AD such as methotrexate and cyclosporine certainly have shown benefit in managing ongoing illness and breaking the cycle of disease.³⁰ The efficacy of these agents points to the role of systemic inflammation in ongoing AD activity. Moreover, the inside-out hypothesis recently has led to the proliferation of promising new therapeutic agents in the pipeline to treat the systemic Th2 inflammation that occurs in severe AD (eg, anti–IL-4/13 receptor antibody, anti–IL-13 antibodies, and biologics targeting IL-12/23, IL-22, and IL-31 receptors).³¹

Final Thoughts

Atopic dermatitis is a multifactorial disease associated with barrier disruption and intense systemic inflammation. It is likely that both the inside-out and outside-in hypotheses hold true in different subsets of AD patients. It is clear that some individuals are born with filaggrin defects that sufficiently trigger systemic inflammation, resulting in AD. On the other hand, there are clearly some individuals with inflammatory dysregulation that results in systemic inflammation and secondary barrier disruption. Until we can determine the genomic triggering or promoting event in each individual patient, large-scale introduction of active prevention and severity reduction strategies may not be realistic. In the meantime, we can approach AD in childhood from the inside out, through appropriate treatment of systemic inflammation of AD, and from the outside in, with treatment and prevention via emollient use in newborns.

Atopic dermatitis (AD) is a multifactorial inflammatory disorder with an estimated prevalence of 279,889,120 cases worldwide.1 Most cases of AD begin in early childhood (with almost 85% developing by 5 years of age),² but recent studies have found that 40% to over 80% of cases persist into adulthood.^1,3,4 Although a previous study focused largely on T helper type 1/T helper type 2 (Th2) immune dysregulation as the pathogenesis of the disease,⁵ disruption of the skin barrier and systemic inflammation are at the center of current AD research. In AD, breakdown of the skin barrier results in increased transepidermal water loss, reduced skin hydration, and increased antigen presentation by Langerhans cells initiating inflammation.6-8 The cascade largely activated is the Th2 and T helper type 22 cascade with resultant cytokine release (ie, IL-4, IL-13, IL-2, IL-8, IL-10, IL-17, IL-22, tumor necrosis factor α, interferon γ).^9,10 In active AD, Th2 inflammation and barrier breakdown result in reduced filaggrin and claudin 1 expression, resulting in further exacerbation of the barrier defect and enhancing the risk of development of asthma and hay fever as well as transcutaneous sensitization to a variety of food allergens (eg, peanuts).^9,11,12 Although all of these immunologic features are well established in AD, controversy remains as to whether AD is caused by systemic inflammation triggering barrier dysfunction (the “inside-out” hypothesis) or from the epidermal skin barrier disruption triggering immunologic imbalance (the “outside-in” hypothesis).

Inside-Out Hypothesis

While barrier impairment appears to occur in all patients with AD, it still is unclear how AD begins. The inside-out hypothesis suggests that cutaneous inflammation precedes barrier impairment and in fact may result in an impaired skin barrier. It has previously been reported that inflammatory states weaken the barrier by downregulating filaggrin production in the skin.¹³ Barrier disruption may be accompanied by transcutaneous penetration of allergens and increased Staphylococcus aureus counts. Recently, mutations and polymorphisms of inflammatory genes have been linked to AD (eg, single nucleotide polymorphisms of the IL4RA [interleukin 4 receptor, alpha] and CD14 [cluster of differentiation 14] genes, the serine protease inhibitor SPINK5 [serine peptidase inhibitor, Kazal type 5], RANTES [chemokine (C-C motif) ligand 5], IL-4, IL-13).¹⁴ These alterations highlight the role of systemic inflammation in triggering AD.

Outside-In Hypothesis

The outside-in hypothesis suggests that the impaired skin barrier precedes AD and is required for immune dysregulation to occur. This hypothesis was largely advanced by a study demonstrating that deactivating mutations of the filaggrin gene were linked to nearly 20% of AD cases in Northern European populations.15 Filaggrin (chromosome 1q21.3) performs an essential function in the skin barrier through its differential cleavage and the breakdown and release of natural moisturizing factor.¹⁶ Filaggrin gene mutations are associated with persistent AD, and it has been posited that environmental factors such as temperature and humidity also can affect filaggrin production as it relates to barrier function.17-19 Skin barrier disruption results in increased cutaneous and systemic Th2 responses (ie, IL-4/13), with thymic stromal lymphopoietin as the potential mechanism of Th2 cell recruitment.^10,20 Inflammatory Th2 cells triggered by an impaired skin barrier also may predispose patients to the development of allergic diseases such as asthma, in line with Atopic March, or the progression of AD to other forms of atopy (eg, food allergy, asthma).^5,7,21-23

The outside-in hypothesis may only explain the root pathogenesis of AD in a subset of patients, however, as only 1 in 5 cases of AD in Northern European and Asian populations are associated with underlying filaggrin mutations (which are only present in about 10% of those who are unaffected by AD).¹⁵ Filaggrin does not appear to account for the basis of AD in all cases. In a study of 762 newborns in Cincinnati, Ohio, 39% of children with at least one parent with atopy developed AD by 3 years of age, about quadruple of what would be projected based on filaggrin defects in general population studies, which are noted in only about 10% of white individuals.²⁴ Furthermore, less than 5% of patients of African descent have mutations of the filaggrin 1 gene.²⁵

Implications for the Prevention and Treatment of Atopic Dermatitis

Preventative strategies for AD currently are in development. Atopic dermatitis may be unpreventable because the in utero environment triggers some of the barrier alterations, which can be noted as early as 2 days following birth and will predict early-onset AD. The putative mechanism is via Th2 cytokines (IL-4, IL-13).²⁶

Certainly, application of over-the-counter and prescription emollients are mainstays of treatment for AD and may suffice as monotherapy in cases of mild disease. In a recent randomized trial in the United States and the United Kingdom, emollients were used in newborns considered at high risk for AD (family history of atopy) until 6 months of age.²⁷ The risk of AD development was reduced by half, irrespective of the emollient used. Unfortunately, 21.8% of children without a family history of atopy will develop AD; therefore, not all cases can be prevented if use of emollients is limited to newborns with a family history of atopy.²⁸ Long-term follow-up is needed to track whether emollient use in newborns will prevent AD indefinitely.

Prevention of AD onset using systemic interventions has also been investigated. Probiotics have been suggested as a means to modify the gut microbiota and reduce systemic and mucosal inflammation. Lactobacillus reuteri taken prenatally by pregnant women and by newborns has shown mild benefit in preventing some forms of AD.29 Although they are not approved by the US Food and Drug Administration for this indication, systemic interventions for moderate-to-severe AD such as methotrexate and cyclosporine certainly have shown benefit in managing ongoing illness and breaking the cycle of disease.³⁰ The efficacy of these agents points to the role of systemic inflammation in ongoing AD activity. Moreover, the inside-out hypothesis recently has led to the proliferation of promising new therapeutic agents in the pipeline to treat the systemic Th2 inflammation that occurs in severe AD (eg, anti–IL-4/13 receptor antibody, anti–IL-13 antibodies, and biologics targeting IL-12/23, IL-22, and IL-31 receptors).³¹

Final Thoughts

Atopic dermatitis is a multifactorial disease associated with barrier disruption and intense systemic inflammation. It is likely that both the inside-out and outside-in hypotheses hold true in different subsets of AD patients. It is clear that some individuals are born with filaggrin defects that sufficiently trigger systemic inflammation, resulting in AD. On the other hand, there are clearly some individuals with inflammatory dysregulation that results in systemic inflammation and secondary barrier disruption. Until we can determine the genomic triggering or promoting event in each individual patient, large-scale introduction of active prevention and severity reduction strategies may not be realistic. In the meantime, we can approach AD in childhood from the inside out, through appropriate treatment of systemic inflammation of AD, and from the outside in, with treatment and prevention via emollient use in newborns.