Treating A Patient With Blisters And Papules On The Soles

By Gary “Dock” Dockery, DPM, FACFAS

A Guide To The Differential Diagnosis

      Vesicular tinea pedis. This is a common misdiagnosis but one may see this concurrently with dyshidrotic dermatitis. Dyshidrotic dermatitis occasionally resolves with the treatment of a tinea pedis infection and then relapses when the fungal infection recurs. This supports the existence of this reaction pattern. In regard to patients who have a vesicular reaction to intradermal trichophytin testing, less than one-third have experienced a resolution of pompholyx after treatment with antifungal agents. Examination of the lesions using potassium hydroxide wet mounts or periodic Acid Schiff reactions will be negative in most cases of isolated dyshidrotic dermatitis.       Palmoplantar pustular psoriasis. This chronic condition affects palms and soles, and may have periods of remission and exacerbation. It is characterized by sterile pustules. New pustules are usually yellow and the older pustules are brown. This is in contrast to dyshidrotic dermatitis in which tense vesicles may dry and crust over. Palmoplantar pustular psoriasis is strongly associated with cigarette smoking and is more common among females. This condition is difficult to treat effectively and one can diagnose it with a punch biopsy.       Classic erythema multiforme. This condition consists of targetoid eruptions affecting distal acral skin. It represents an immunologic reaction, most commonly to infection with herpes simplex. While central vesiculation may occur with erythema multiforme, targetoid lesions are lacking in this case of dyshidrotic dermatitis as is clinical evidence of an eruption of herpes simplex.       Bullous pemphigoid. This can involve the palms and soles, but the disorder is more common among the elderly, especially among those with multiple comorbidities. Such a diagnosis would be unlikely in an otherwise healthy young woman. Bullous pemphigoid would also probably involve additional areas of the body and is unlikely to be confined to the palms and soles.       Hand-foot-mouth disease. This is usually caused by Coxsackie A16 but can be caused by other Coxsackie viruses and Enterovirus 71. It is a self-limited disease with resultant acquired immunity. This disease is most common among young children but one may see this with some frequency up until puberty. Adults can get it but this is much less common. The early lesions are usually pink with a distinct mauve or purple border.       Irritant contact dermatitis. This is much more prevalent on the hands and is uncommon on the feet, especially in the non-weightbearing areas. Primary irritant dermatitis results from direct contact to the skin. It affects individuals exposed to specific irritants and generally produces discomfort immediately following exposure. Although irritant contact dermatitis is caused mostly by chemicals (such as acids, alkalis, solvents and oxidants), plants (such as hot peppers, garlic and tobacco) have also been implicated.       Insect bites and stings. These may involve both the feet and hands, and cause significant pruritus. Most bites are on the dorsum of the hand and foot rather than the palmoplantar surfaces. Scabies and fleas may bite and burrow into the skin of the fingers, toes, palms and soles. In most cases, the reactions from bites are much more erythematous and inflamed with fewer vesicles than one would find with dyshidrotic dermatitis.

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