Boy With Rash on Forefeet

What's Your Diagnosis?
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HISTORY

A 7-year-old boy presented with a 1-year history of a rash on his forefeet. The rash was not pruritic, but there was an occasional burning sensation in the affected area. The child was active in sports. His past health was unremarkable. There was no family history of skin problems.

PHYSICAL EXAMINATION

Dry, slightly erythematous, hyperkeratotic, and fissured plantar aspects of the big toes and forefeet were observed. The web spaces between the toes were not involved. Remaining examination findings were unremarkable.

What’s Your Diagnosis?

(Answer and discussion on next page)

ANSWER: Juvenile plantar dermatosis

The term juvenile plantar dermatosis was coined by Mackie and Husain to denote a condition characterized by symmetric scaling, fissuring, and itching or burning of the weight-bearing areas of the feet; the condition occurs primarily in school-aged children.¹ Juvenile plantar dermatosis also is referred to as dermatitis plantaris sicca, sweaty sock dermatitis, sneaker feet, and wet and dry syndrome.^2,3

EPIDEMIOLOGY

Juvenile plantar dermatosis is a common skin disease that typically affects children between 3 and 14 years of age, with a peak incidence between 4 and 7 years.^3-5 The condition is rarely observed in adults.² Boys are affected more often than girls.^2,3,6 There is seasonal variation, with worsening of the condition during the summer and in cold weather.^2,3,7

ETIOLOGY

The exact etiology is unknown. It is believed that the condition may result from alternating excessive sweat retention and subsequent moisture loss (evaporation), leading to chapping of the skin and cracking of the stratum corneum.³ As such, wearing occlusive footwear and having prolonged exposure to moist shoes or socks are predisposing factors. The most common scenario is a child who runs around at school or outside, then comes home and removes his shoes and sweaty socks; he then walks around barefoot, with evaporation occurring from the moist feet and subsequent dehydration and fissuring of the feet (akin to licking one’s lips, resulting in chapped lips). Friction or mechanical trauma plays a role, since the condition is most common in the weight-bearing areas of the forefoot.^2,3,5,8 Atopic dermatitis also is a risk factor.^2-4 There is a genetic predisposition for some individuals, and the condition has been described in twins.⁹ It also is more common in children who have a first-degree relative with atopic dermatitis.¹⁰

HISTOPATHOLOGY

Histologic examination revealed acanthosis with hyperkeratosis and lymphocytic infiltrate in the dermis around the capillaries and sweat ducts.^3,6 There was no spongiosis.³

CLINICAL MANIFESTATIONS

Juvenile plantar dermatosis is characterized by a triad of erythema, hyperkeratosis, and fissures in the plantar surfaces of the toes and the anterior part of the soles in the weight-bearing areas.^3,6,7,11 Some patients complain of itching or burning in the affected areas. Lesions often appear as dry, red, shiny, glazed patches.⁶ In chronic cases, scaling and fissuring may become apparent.⁶ Pain may result from fissures.³ In severe cases, the heels also may be affected.³ The interdigital spaces, the dorsum of the foot, and the instep, however, are spared.^2,6 The condition usually is bilateral and symmetric.^4,5,7 Children with juvenile plantar dermatosis may have hyperhidrosis and often wear socks and occlusive synthetic footwear followed by walking around barefoot.^10,11

DIAGNOSIS

The diagnosis usually is based on history and clinical findings. Further diagnostic workup usually is not necessary. Occasionally, potassium hydroxide wet-mount examination of scrapings of the lesion’s active border may be required to distinguish juvenile plantar dermatosis from tinea pedis.⁷ Skin tests, patch tests, swabs, and biopsy generally are not beneficial.³ Referral to a dermatologist should be considered if diagnosis is uncertain.

DIFFERENTIAL DIAGNOSIS

Juvenile plantar dermatosis has to be differentiated from tinea pedis, which may manifest as erythema and scaling of the plantar foot.⁷ In tinea pedis, scaling and maceration often are seen in the instep and interdigital spaces.^6,7 There may be associated onychomycosis. In contrast to juvenile plantar dermatosis, tinea pedis is uncommon in prepubertal children.²

Atopic dermatitis is a chronic, relapsing dermatosis characterized by pruritus, erythema, vesiculation, exudation, excoriation, crusting, scaling, and sometimes lichenification. In childhood, sites of predilection include the neck, the antecubital region, and the popliteal fossae. When atopic dermatitis involves the foot, the lesion occurs primarily on the dorsum of the toes and the back of the foot.⁷ The sole of the foot generally is spared.

Allergic contact dermatitis presents with well-defined erythema, lichenification, and severe pruritus.⁶ The condition may be caused by exposure to chemicals contained in leather or the rubber in shoes.² Allergic contact dermatitis occurs most commonly on the dorsa of the feet.^6,7 Typically, interdigital spaces are spared because they have no contact with shoes.

In plantar psoriasis, lesions often extend onto the arches of the feet.³ Psoriatic lesions often appear elsewhere on the body. Psoriatic lesions are characterized by sharply demarcated erythematous plaques with adherent silvery scales on extensor surfaces. Removal of the scales results in fine punctate bleeding. The lesions usually are symmetrically distributed and often are pruritic. Affected patients may have nail dystrophy and psoriatic arthritis.

Other differential diagnoses include pityriasis rubra pilaris, keratolysis exfoliativa, lichen planus, dyshidrotic eczema, keratoderma, and id reaction.^6,7 The distinctive features of each condition allow a straightforward differentiation from juvenile plantar dermatosis.

MANAGEMENT

Patients should be advised not to wear occlusive footwear and socks made of synthetic fibers.^3,7 They should wear cotton socks and light leather shoes or sandals instead.⁴ Patients should remove their shoes when indoors and change their all-cotton socks whenever they are damp.⁷ Application of an emollient cream (eg, containing urea) when socks and shoes are removed often is beneficial.¹⁰ Mild topical corticosteroid ointments, or calcineurin inhibitors such as tacrolimus ointment and pimecrolimus cream, usually are effective for the relief of pruritus and inflammation.^6,7,9,11

PROGNOSIS

Juvenile plantar dermatosis is characterized by flares and remissions.³ It is self-limiting and generally resolves by 16 years of age.¹⁰

REFERENCES:

1. Mackie RM, Husain SL. Juvenile plantar dermatosis: a new entity? Clin Exp Dermatol. 1976;1(3):253-260.

2. Fritsch PO, Reider N. Juvenile plantar dermatosis. In: Bolognia JL, Jorizzo JL, Rapini RP, eds. Dermatology. Philadelphia, PA: Mosby Elsevier; 2003:224-226.

3. Tennstedt D. Juvenile plantar dermatosis. In: Harper J, Oranje A, Prose NS, eds. Textbook of Pediatric Dermatology. 2nd ed. Oxford, England: Wiley-Blackwell; 2006:345-348.

4. Guenst B. Common pediatric foot dermatoses. J Pediatr Health Care. 1999;13(2):68-71.

5. Holden CA, Berth-Jones J. Eczema, lichenification, prurigo and erythroderma. In: Burns T, Breathnach S, Cox N, Griffith C, eds. Rook’s Textbook of Dermatology. Vol 1. 7th ed. Oxford, England: Blackwell Publishing; 2004:17.1-17.55.

6. Kalia S, Adams SP. Dermcase. Juvenile plantar dermatosis. Can Fam Physician. September 2005;51:1203, 1213.

7. Eczematous eruptions in childhood. In: Hurwitz Clinical Pediatric Dermatology: A Textbook of Skin Disorders of Childhood and Adolescence. 3rd ed. Philadelphia, PA: Elsevier Saunders; 2006:49-84.

8. Shipley DR, Kennedy CT. Juvenile plantar dermatosis responding to topical tacrolimus ointment. Clin Exp Dermatol. 2006;31(3):453-454.

9. Stankler L. Juvenile plantar dermatosis in identical twins. Br J Dermatol. 1978;99(5):585.

10. Browning J, Bree A. Juvenile plantar dermatosis. In: Irvine AD, Hoeger PH, Yan AC, eds. Harper’s Textbook of Pediatric Dermatology. 3rd ed. Oxford, England: Wiley-Blackwell; 2011:43.1-43.2.

11. Leung AK. Juvenile plantar dermatosis. In: Leung AK, ed. Common Problems in Ambulatory Pediatrics: Specific Clinical Problems. Vol 2. New York, NY: Nova Science Publishers; 2011:271-274.