Jennifer Mancuso, MD

The Diagnosis: Actinic Prurigo

Actinic prurigo is an idiopathic photodermatosis triggered by UV exposure that primarily affects sun-exposed areas of the skin.^1,2 It typically presents as pruritic papules, plaques, and nodules, with most patients also experiencing oral tingling and pain.³ In more severe cases, it can progress to include conjunctival disease, scarring, and cheilitis.¹ A study of ocular findings among children with actinic pruritus reported that photophobia was one of the most important features,⁴ which was present in our patient. The face, especially over the zygomatic arches, nasal bridge, and lower lip, commonly is affected.1 Secondary lichenification or eczematization may occur.⁵ In our patient, the combination of conjunctivitis, cheilitis, and an eruption on sun-exposed skin were crucial in making the diagnosis.

Most cases present in patients younger than 10 years. It most commonly is seen in American Indians in North America, Central America, and South America.² After the diagnosis was considered in our patient, the family was asked about their ancestry and confirmed that both of the patient’s maternal and paternal grandparents were of American Indian descent. There also is a strong genetic component; the HLA-DR4 allele variant is present in 90% of cases, especially DRB1*0407, which is seen in 60% of cases.^1,6 In our patient, testing revealed HLA-DR4, DRB1*04 positivity. We further hypothesized that his mother’s photosensitive rash may have been actinic prurigo as opposed to polymorphous light eruption, which could explain the lack of response to hydroxychloroquine.

The diagnosis of actinic prurigo usually is made clinically. A skin biopsy typically is not necessary but would show hyperkeratosis, spongiosis, and acanthosis with a lymphocytic perivascular infiltrate. Biopsies of the lip classically show lymphoid germinal centers in the lamina propria, which can help distinguish actinic prurigo from polymorphous light eruption.¹

In our patient, the differential diagnosis included polymorphous light eruption, connective tissue disease such as lupus erythematosus or dermatomyositis, porphyria such as erythropoietic protoporphyria, and allergic contact dermatitis. Polymorphous light eruption was ruled out by the oral and ocular manifestations, which are not atypical for this diagnosis. The patient’s laboratory results displayed unremarkable antinuclear antibodies, creatine kinase, aldolase, and extractable nuclear antigens, which made connective tissue disease unlikely. Furthermore, a porphyria screen for total plasma porphyrins and whole blood protoporphyrin was negative, which helped rule out porphyria. Allergic contact dermatitis seemed less likely given the lack of improvement with topical steroids. Overall, the clinical presentation in a patient with relevant family ancestry and HLA-DR4 positivity supported a diagnosis of actinic prurigo.⁷

To manage the condition in our patient, strict photoprotection was recommended as well as the application of triamcinolone ointment 0.025% to the affected areas twice daily until the skin symptoms improved. For acute flares, other treatment considerations include topical tacrolimus, oral antihistamines, and oral corticosteroids. Some success has been reported with cyclosporine and azathioprine. For severe disease, thalidomide is the recommended treatment; it is effective in pediatric patients at dosages of 50 to 100 mg daily, but the dose has not yet been standardized for this age group.^8,9 Many adult patients initially are controlled with 100 to 200 mg daily, which can be tapered down to a dosage of 25 to 50 mg weekly with few adverse effects; however, the overall substantial side effects of thalidomide limit its use in both pediatric and adult populations.^1,2 Newer studies have suggested promising results with dupilumab, especially when actinic prurigo presents with high IgE levels or eosinophils on histology.^7,10 In our patient, the IgE level was normal.

The Diagnosis: Actinic Prurigo

Actinic prurigo is an idiopathic photodermatosis triggered by UV exposure that primarily affects sun-exposed areas of the skin.^1,2 It typically presents as pruritic papules, plaques, and nodules, with most patients also experiencing oral tingling and pain.³ In more severe cases, it can progress to include conjunctival disease, scarring, and cheilitis.¹ A study of ocular findings among children with actinic pruritus reported that photophobia was one of the most important features,⁴ which was present in our patient. The face, especially over the zygomatic arches, nasal bridge, and lower lip, commonly is affected.1 Secondary lichenification or eczematization may occur.⁵ In our patient, the combination of conjunctivitis, cheilitis, and an eruption on sun-exposed skin were crucial in making the diagnosis.

Most cases present in patients younger than 10 years. It most commonly is seen in American Indians in North America, Central America, and South America.² After the diagnosis was considered in our patient, the family was asked about their ancestry and confirmed that both of the patient’s maternal and paternal grandparents were of American Indian descent. There also is a strong genetic component; the HLA-DR4 allele variant is present in 90% of cases, especially DRB1*0407, which is seen in 60% of cases.^1,6 In our patient, testing revealed HLA-DR4, DRB1*04 positivity. We further hypothesized that his mother’s photosensitive rash may have been actinic prurigo as opposed to polymorphous light eruption, which could explain the lack of response to hydroxychloroquine.

The diagnosis of actinic prurigo usually is made clinically. A skin biopsy typically is not necessary but would show hyperkeratosis, spongiosis, and acanthosis with a lymphocytic perivascular infiltrate. Biopsies of the lip classically show lymphoid germinal centers in the lamina propria, which can help distinguish actinic prurigo from polymorphous light eruption.¹

In our patient, the differential diagnosis included polymorphous light eruption, connective tissue disease such as lupus erythematosus or dermatomyositis, porphyria such as erythropoietic protoporphyria, and allergic contact dermatitis. Polymorphous light eruption was ruled out by the oral and ocular manifestations, which are not atypical for this diagnosis. The patient’s laboratory results displayed unremarkable antinuclear antibodies, creatine kinase, aldolase, and extractable nuclear antigens, which made connective tissue disease unlikely. Furthermore, a porphyria screen for total plasma porphyrins and whole blood protoporphyrin was negative, which helped rule out porphyria. Allergic contact dermatitis seemed less likely given the lack of improvement with topical steroids. Overall, the clinical presentation in a patient with relevant family ancestry and HLA-DR4 positivity supported a diagnosis of actinic prurigo.⁷

To manage the condition in our patient, strict photoprotection was recommended as well as the application of triamcinolone ointment 0.025% to the affected areas twice daily until the skin symptoms improved. For acute flares, other treatment considerations include topical tacrolimus, oral antihistamines, and oral corticosteroids. Some success has been reported with cyclosporine and azathioprine. For severe disease, thalidomide is the recommended treatment; it is effective in pediatric patients at dosages of 50 to 100 mg daily, but the dose has not yet been standardized for this age group.^8,9 Many adult patients initially are controlled with 100 to 200 mg daily, which can be tapered down to a dosage of 25 to 50 mg weekly with few adverse effects; however, the overall substantial side effects of thalidomide limit its use in both pediatric and adult populations.^1,2 Newer studies have suggested promising results with dupilumab, especially when actinic prurigo presents with high IgE levels or eosinophils on histology.^7,10 In our patient, the IgE level was normal.

The Diagnosis: Actinic Prurigo

Actinic prurigo is an idiopathic photodermatosis triggered by UV exposure that primarily affects sun-exposed areas of the skin.^1,2 It typically presents as pruritic papules, plaques, and nodules, with most patients also experiencing oral tingling and pain.³ In more severe cases, it can progress to include conjunctival disease, scarring, and cheilitis.¹ A study of ocular findings among children with actinic pruritus reported that photophobia was one of the most important features,⁴ which was present in our patient. The face, especially over the zygomatic arches, nasal bridge, and lower lip, commonly is affected.1 Secondary lichenification or eczematization may occur.⁵ In our patient, the combination of conjunctivitis, cheilitis, and an eruption on sun-exposed skin were crucial in making the diagnosis.

Most cases present in patients younger than 10 years. It most commonly is seen in American Indians in North America, Central America, and South America.² After the diagnosis was considered in our patient, the family was asked about their ancestry and confirmed that both of the patient’s maternal and paternal grandparents were of American Indian descent. There also is a strong genetic component; the HLA-DR4 allele variant is present in 90% of cases, especially DRB1*0407, which is seen in 60% of cases.^1,6 In our patient, testing revealed HLA-DR4, DRB1*04 positivity. We further hypothesized that his mother’s photosensitive rash may have been actinic prurigo as opposed to polymorphous light eruption, which could explain the lack of response to hydroxychloroquine.

The diagnosis of actinic prurigo usually is made clinically. A skin biopsy typically is not necessary but would show hyperkeratosis, spongiosis, and acanthosis with a lymphocytic perivascular infiltrate. Biopsies of the lip classically show lymphoid germinal centers in the lamina propria, which can help distinguish actinic prurigo from polymorphous light eruption.¹

In our patient, the differential diagnosis included polymorphous light eruption, connective tissue disease such as lupus erythematosus or dermatomyositis, porphyria such as erythropoietic protoporphyria, and allergic contact dermatitis. Polymorphous light eruption was ruled out by the oral and ocular manifestations, which are not atypical for this diagnosis. The patient’s laboratory results displayed unremarkable antinuclear antibodies, creatine kinase, aldolase, and extractable nuclear antigens, which made connective tissue disease unlikely. Furthermore, a porphyria screen for total plasma porphyrins and whole blood protoporphyrin was negative, which helped rule out porphyria. Allergic contact dermatitis seemed less likely given the lack of improvement with topical steroids. Overall, the clinical presentation in a patient with relevant family ancestry and HLA-DR4 positivity supported a diagnosis of actinic prurigo.⁷

To manage the condition in our patient, strict photoprotection was recommended as well as the application of triamcinolone ointment 0.025% to the affected areas twice daily until the skin symptoms improved. For acute flares, other treatment considerations include topical tacrolimus, oral antihistamines, and oral corticosteroids. Some success has been reported with cyclosporine and azathioprine. For severe disease, thalidomide is the recommended treatment; it is effective in pediatric patients at dosages of 50 to 100 mg daily, but the dose has not yet been standardized for this age group.^8,9 Many adult patients initially are controlled with 100 to 200 mg daily, which can be tapered down to a dosage of 25 to 50 mg weekly with few adverse effects; however, the overall substantial side effects of thalidomide limit its use in both pediatric and adult populations.^1,2 Newer studies have suggested promising results with dupilumab, especially when actinic prurigo presents with high IgE levels or eosinophils on histology.^7,10 In our patient, the IgE level was normal.

Practice Gap

Frictional, symmetric, asymptomatic, erythematous macules of the hands and feet can be mistaken for perniolike lesions associated with COVID-19, commonly known as COVID toes. However, in a low-risk setting without other associated symptoms or concerning findings on examination, consider and inquire about frequent use of a swimming pool. This activity can lead to localized pressure- and friction-induced erythema on palmar and plantar surfaces, called “pool palms and feet,” expanding on the already-named lesion “pool palms”—an entity that is distinct from COVID toes.

Technique for Diagnosis

We evaluated 4 patients in the outpatient setting who presented with localized, patterned, erythematous lesions of the hands or feet, or both, during the COVID-19 pandemic. The parents of our patients were concerned that the rash represented “COVID fingers and toes,” which are perniolike lesions seen in patients with suspected or confirmed current or prior COVID-19.¹

Pernio, also known as chilblains, is a superficial inflammatory vascular response, usually in the setting of exposure to cold.² This phenomenon usually appears as erythematous or violaceous macules and papules on acral skin, particularly on the dorsum and sides of the fingers and toes, with edema, vesiculation, and ulceration in more severe cases. Initially, it is pruritic and painful at times.

With COVID toes, there often is a delayed presentation of perniolike lesions after the onset of other COVID-19 symptoms, such as fever, cough, headache, and sore throat.^2,3 It has been described more often in younger patients and those with milder disease. However, because our patients had no known exposure to SARS-CoV-2 or other associated symptoms, our suspicion was low.

The 4 patients we evaluated—aged 4 to 12 years and in their usual good health—had blanchable erythema of the palmar fingers, palmar eminences of both hands, and plantar surfaces of both feet (Figure). There was no swelling or tenderness, and the lesions had no violaceous coloration, vesiculation, or ulceration. There was no associated pruritus or pain. One patient reported rough texture and mild peeling of the hands.

Upon further inquiry, the patients reported a history of extended time spent in home swimming pools, including holding on to the edge of the pool, due to limitation of activities because of COVID restrictions. One parent noted that the pool that caused the rash had a rough nonslip surface, whereas other pools that the children used, which had a smoother surface, caused no problems.

The morphology of symmetric blanching erythema in areas of pressure and friction, in the absence of a notable medical history, signs, or symptoms, was consistent with a diagnosis of pool palms, which has been described in the medical literature.^4-9 Pool palms can affect the palms and soles, which are subject to substantial friction, especially when a person is getting in and out of the pool. There is a general consensus that pool palms is a frictional dermatitis affecting children because the greater fragility of their skin is exacerbated by immersion in water.^4-9

Pool palms and feet is benign. Only supportive care, with cessation of swimming and application of emollients, is necessary.

Apart from COVID-19, other conditions to consider in a patient with erythematous lesions of the palms and soles include eczematous dermatitis; neutrophilic eccrine hidradenitis; and, if lesions are vesicular, hand-foot-and-mouth disease. Juvenile plantar dermatosis, which is thought to be due to moisture with occlusion in shoes, also might be considered but is distinguished by more scales and fissures that can be painful.

Location of the lesions is a critical variable. The patients we evaluated had lesions primarily on palmar and plantar surfaces where contact with pool surfaces was greatest, such as at bony prominences, which supported a diagnosis of frictional dermatitis, such as pool palms and feet. A thorough history and physical examination are helpful in determining the diagnosis.

Practical Implications

It is important to consider and recognize this localized pressure phenomenon of pool palms and feet, thus obviating an unnecessary workup or therapeutic interventions. Specifically, a finding of erythematous asymptomatic macules, with or without scaling, on bony prominences of the palms and soles is more consistent with pool palms and feet.

Pernio and COVID toes both present as erythematous to violaceous papules and macules, with edema, vesiculation, and ulceration in severe cases, often on the dorsum and sides of fingers and toes; typically the conditions are pruritic and painful at times.

Explaining the diagnosis of pool palms and feet and sharing one’s experience with similar cases might help alleviate parental fear and anxiety during the COVID-19 pandemic.

Practice Gap

Frictional, symmetric, asymptomatic, erythematous macules of the hands and feet can be mistaken for perniolike lesions associated with COVID-19, commonly known as COVID toes. However, in a low-risk setting without other associated symptoms or concerning findings on examination, consider and inquire about frequent use of a swimming pool. This activity can lead to localized pressure- and friction-induced erythema on palmar and plantar surfaces, called “pool palms and feet,” expanding on the already-named lesion “pool palms”—an entity that is distinct from COVID toes.

Technique for Diagnosis

We evaluated 4 patients in the outpatient setting who presented with localized, patterned, erythematous lesions of the hands or feet, or both, during the COVID-19 pandemic. The parents of our patients were concerned that the rash represented “COVID fingers and toes,” which are perniolike lesions seen in patients with suspected or confirmed current or prior COVID-19.¹

Pernio, also known as chilblains, is a superficial inflammatory vascular response, usually in the setting of exposure to cold.² This phenomenon usually appears as erythematous or violaceous macules and papules on acral skin, particularly on the dorsum and sides of the fingers and toes, with edema, vesiculation, and ulceration in more severe cases. Initially, it is pruritic and painful at times.

With COVID toes, there often is a delayed presentation of perniolike lesions after the onset of other COVID-19 symptoms, such as fever, cough, headache, and sore throat.^2,3 It has been described more often in younger patients and those with milder disease. However, because our patients had no known exposure to SARS-CoV-2 or other associated symptoms, our suspicion was low.

The 4 patients we evaluated—aged 4 to 12 years and in their usual good health—had blanchable erythema of the palmar fingers, palmar eminences of both hands, and plantar surfaces of both feet (Figure). There was no swelling or tenderness, and the lesions had no violaceous coloration, vesiculation, or ulceration. There was no associated pruritus or pain. One patient reported rough texture and mild peeling of the hands.

Upon further inquiry, the patients reported a history of extended time spent in home swimming pools, including holding on to the edge of the pool, due to limitation of activities because of COVID restrictions. One parent noted that the pool that caused the rash had a rough nonslip surface, whereas other pools that the children used, which had a smoother surface, caused no problems.

The morphology of symmetric blanching erythema in areas of pressure and friction, in the absence of a notable medical history, signs, or symptoms, was consistent with a diagnosis of pool palms, which has been described in the medical literature.^4-9 Pool palms can affect the palms and soles, which are subject to substantial friction, especially when a person is getting in and out of the pool. There is a general consensus that pool palms is a frictional dermatitis affecting children because the greater fragility of their skin is exacerbated by immersion in water.^4-9

Pool palms and feet is benign. Only supportive care, with cessation of swimming and application of emollients, is necessary.

Apart from COVID-19, other conditions to consider in a patient with erythematous lesions of the palms and soles include eczematous dermatitis; neutrophilic eccrine hidradenitis; and, if lesions are vesicular, hand-foot-and-mouth disease. Juvenile plantar dermatosis, which is thought to be due to moisture with occlusion in shoes, also might be considered but is distinguished by more scales and fissures that can be painful.

Location of the lesions is a critical variable. The patients we evaluated had lesions primarily on palmar and plantar surfaces where contact with pool surfaces was greatest, such as at bony prominences, which supported a diagnosis of frictional dermatitis, such as pool palms and feet. A thorough history and physical examination are helpful in determining the diagnosis.

Practical Implications

It is important to consider and recognize this localized pressure phenomenon of pool palms and feet, thus obviating an unnecessary workup or therapeutic interventions. Specifically, a finding of erythematous asymptomatic macules, with or without scaling, on bony prominences of the palms and soles is more consistent with pool palms and feet.

Pernio and COVID toes both present as erythematous to violaceous papules and macules, with edema, vesiculation, and ulceration in severe cases, often on the dorsum and sides of fingers and toes; typically the conditions are pruritic and painful at times.

Explaining the diagnosis of pool palms and feet and sharing one’s experience with similar cases might help alleviate parental fear and anxiety during the COVID-19 pandemic.

Practice Gap

Frictional, symmetric, asymptomatic, erythematous macules of the hands and feet can be mistaken for perniolike lesions associated with COVID-19, commonly known as COVID toes. However, in a low-risk setting without other associated symptoms or concerning findings on examination, consider and inquire about frequent use of a swimming pool. This activity can lead to localized pressure- and friction-induced erythema on palmar and plantar surfaces, called “pool palms and feet,” expanding on the already-named lesion “pool palms”—an entity that is distinct from COVID toes.

Technique for Diagnosis

We evaluated 4 patients in the outpatient setting who presented with localized, patterned, erythematous lesions of the hands or feet, or both, during the COVID-19 pandemic. The parents of our patients were concerned that the rash represented “COVID fingers and toes,” which are perniolike lesions seen in patients with suspected or confirmed current or prior COVID-19.¹

Pernio, also known as chilblains, is a superficial inflammatory vascular response, usually in the setting of exposure to cold.² This phenomenon usually appears as erythematous or violaceous macules and papules on acral skin, particularly on the dorsum and sides of the fingers and toes, with edema, vesiculation, and ulceration in more severe cases. Initially, it is pruritic and painful at times.

With COVID toes, there often is a delayed presentation of perniolike lesions after the onset of other COVID-19 symptoms, such as fever, cough, headache, and sore throat.^2,3 It has been described more often in younger patients and those with milder disease. However, because our patients had no known exposure to SARS-CoV-2 or other associated symptoms, our suspicion was low.

The 4 patients we evaluated—aged 4 to 12 years and in their usual good health—had blanchable erythema of the palmar fingers, palmar eminences of both hands, and plantar surfaces of both feet (Figure). There was no swelling or tenderness, and the lesions had no violaceous coloration, vesiculation, or ulceration. There was no associated pruritus or pain. One patient reported rough texture and mild peeling of the hands.

Upon further inquiry, the patients reported a history of extended time spent in home swimming pools, including holding on to the edge of the pool, due to limitation of activities because of COVID restrictions. One parent noted that the pool that caused the rash had a rough nonslip surface, whereas other pools that the children used, which had a smoother surface, caused no problems.

The morphology of symmetric blanching erythema in areas of pressure and friction, in the absence of a notable medical history, signs, or symptoms, was consistent with a diagnosis of pool palms, which has been described in the medical literature.^4-9 Pool palms can affect the palms and soles, which are subject to substantial friction, especially when a person is getting in and out of the pool. There is a general consensus that pool palms is a frictional dermatitis affecting children because the greater fragility of their skin is exacerbated by immersion in water.^4-9

Pool palms and feet is benign. Only supportive care, with cessation of swimming and application of emollients, is necessary.

Apart from COVID-19, other conditions to consider in a patient with erythematous lesions of the palms and soles include eczematous dermatitis; neutrophilic eccrine hidradenitis; and, if lesions are vesicular, hand-foot-and-mouth disease. Juvenile plantar dermatosis, which is thought to be due to moisture with occlusion in shoes, also might be considered but is distinguished by more scales and fissures that can be painful.

Location of the lesions is a critical variable. The patients we evaluated had lesions primarily on palmar and plantar surfaces where contact with pool surfaces was greatest, such as at bony prominences, which supported a diagnosis of frictional dermatitis, such as pool palms and feet. A thorough history and physical examination are helpful in determining the diagnosis.

Practical Implications

It is important to consider and recognize this localized pressure phenomenon of pool palms and feet, thus obviating an unnecessary workup or therapeutic interventions. Specifically, a finding of erythematous asymptomatic macules, with or without scaling, on bony prominences of the palms and soles is more consistent with pool palms and feet.

Pernio and COVID toes both present as erythematous to violaceous papules and macules, with edema, vesiculation, and ulceration in severe cases, often on the dorsum and sides of fingers and toes; typically the conditions are pruritic and painful at times.

Explaining the diagnosis of pool palms and feet and sharing one’s experience with similar cases might help alleviate parental fear and anxiety during the COVID-19 pandemic.