Pompholyx

For 3 days, a 10-year-old boy had an itchy, tense, vesicular rash on the fingers of both hands (A). He was otherwise healthy. He had no exposure to chemicals or plants and no history of recent illness or sick contacts. His medical history was unremarkable. Application of an over-the-counter hydrocortisone cream provided some relief. The mother had had a few episodes of a similar rash during her teenage years. She also had a history of well-controlled atopic dermatitis, with no recent recurrences.

The rash was not inflamed or erythematous. Some of the lesions had formed bullae that were similarly tense and contained a clear fluid. They were mainly located along the lateral and volar aspects of the digits and thumb (B). The remaining physical examination findings were normal.

This child has pompholyx, a recurrent dermatitis that occurs mainly in teenagers and young adults. It is characterized by a noninflammatory but pruritic vesicular or bullous rash with a predilection for the hands and feet.¹ It is usually bilateral and may be symmetrical. The condition frequently develops in the summer.

The vesicles usually persist for 3 to 4 weeks and may occur in crops. In the chronic phase, the skin may have thickened fissured plaques that can be uncomfortable.

Although the cause is unknown, affected patients often have atopy and a patch test that is positive for allergens.² Studies have shown a relationship between pompholyx and exposure to metals, especially nickel, in the diet or in prostheses (such as orthodontic wires). Pompholyx is also called dyshidrotic eczema because it may be associated with excessive sweating of the palms. However, the clear fluid in the vesicles has a physiologic pH and contains protein, unlike sweat. Unlike contact dermatitis, which mainly affects the dorsal surface of the hands, this condition affects the volar and lateral surfaces. It may also mimic a vesicular or id reaction to a dermatophyte infection of the feet.

The clinical course of dyshidrotic eczema can range from mild and self-limited to chronic and severe. In some patients, it can be debilitating. Scratching the lesions can deroof the vesicles and bullae, which may lead to bacterial superinfection.

Patients are advised to avoid exposure to harsh soaps or metals that may worsen the condition. The mainstay of treatment is potent topical corticosteroids and cool compresses.³ Systemic corticosteroids for severe, widespread cases and corticosteroid-sparing medications for long-term use may be needed. Occlusive therapy with pimecrolimus may be useful in patients with severe hand and foot involvement. However, its potential adverse effects preclude it from being first-line therapy. Psoralen plus UVA therapy has also been shown to be beneficial. In the chronic phase, emollients and lubrication can help prevent painful fissures. Despite these measures, the condition can be very frustrating for the patients and their families.

This patient was treated with a wet dressing followed by mometasone cream 0.1%, applied topically once daily for 2 weeks. At follow-up, his symptoms and rash had resolved, leaving only mild postinflammatory hyperpigmentation.