Bubbly Fingers

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Bubbly Fingers

A very thorough study of pompholyx and recommendations on what to do next

Many of us have experienced itchy bumps on the sides of the fingers, a common dermatosis called pompholyx — cause unknown. These investigators studied 120 consecutive French patients with pompholyx, enrolling those with cyclic short-term recurrences of vesicles or bullae on the lateral aspects of the fingers, palms, or soles and excluding those with associated erythema. Patients were age- and sex-matched with controls of unspecified source.

All subjects were examined and asked about such trigger factors as perspiration, smoking, drugs, food, and emotional stress. Lesional skin and skin from the fourth interdigital space were scraped to obtain specimens for fungal culture. Patients with isolated fungi received oral bifonazole. All patients were patch tested and challenged with orally administered nickel sulfate and cobalt sulfate. The relevance of patch-test reactions was tested by elimination and challenge of suspected products. Patients were screened for atopic dermatitis (AD) using defined criteria. Smokers were patch tested to tobacco and asked to stop smoking for 15 days to assess the effects of cessation and reinstitution. If foods or drugs were suspect, two challenges were performed to assess accuracy and relevance.

A palmoplantar sweat disorder was identified in 40% of patients and 7% of controls. Hyperhidrosis was observed in one third of all subjects. Smokers made up 48% of patients but only 28% of controls; 47% of patients and 20% of controls had AD. A dermatophyte was isolated in 19 patients (16%); antifungal treatment cured pompholyx, at least temporarily, in 13. Contact allergy was found in 75% of patients; nickel was the most common allergen. Challenge with oral nickel elicited pompholyx in only two subjects. Overall, allergic contact dermatitis was considered relevant in two thirds of patch-test–positive subjects.

Comment: It’s hard to imagine a better-conceived study of this subject. The authors established prospective criteria for identifying cause and recruited control subjects to establish relevance. A well-written and thought-provoking editorial considers terminology and cause and challenges the concept of "contact pompholyx," particularly with respect to relevance.

Here is what I learned and what I will do now: For a patient with recurrent crops of itchy vesicles and bullae on the palms or soles, I will provide a holding diagnosis of pompholyx, while regarding differential diagnosis as to cause, including tinea and fungal disease (necessitating antifungal therapy), allergic contact dermatitis (necessitating patch tests and allergen avoidance), association with palmoplantar hyperhidrosis (necessitating antiperspirant therapies), association with smoking (necessitating smoking cessation), AD (necessitating topical steroids and irritant avoidance), and internal allergy/drug reaction (rare). Some patients will have more than one trigger. Personal hygiene products contained the relevant allergen in almost half of "contact pompholyx" cases. If erythema is present, I will prescribe fairly potent topical steroids and keep an open mind as to diagnosis and cause, as this additional symptom was not studied.

— Mark V. Dahl, MD

Published in Journal Watch Dermatology February 1, 2008