dermatologic disorders
Tinea Pedis (Athlete's Foot)
Introduction
Tinea pedis is a dermatophyte infection of the feet. Diagnosis is by clinical appearance and sometimes by potassium hydroxide wet mount, particularly if the infection manifests as hyperkeratotic, ulcerative, or vesiculobullous or is not interdigital. Treatment is with topical antifungals, occasionally oral antifungals, moisture reduction, and drying agents. Tinea pedis is the most common Overview of Dermatophytoses because moisture resulting from foot sweating facilitates fungal growth. Tinea pedis may occur as any of 4 clinical forms or in combination: Chronic hyperkeratotic Chronic intertriginous Acute ulcerative Vesiculobullous Chronic hyperkeratotic tinea pedisdue toTrichophyton rubrumcauses a distinctive pattern of lesion, manifesting as scaling and thickening of the soles, which often extends beyond the plantar surface in a moccasin distribution. Patients who are not responding as expected to antifungal therapy may have another less common cause of plantar rash. Differential diagnosis is sterile maceration (due to hyperhidrosis and occlusive footgear), Contact Dermatitis (due to type IV delayed hypersensitivity to various materials in shoes, particularly adhesive cement, thiuram compounds in footwear that contains rubber, and chromate tanning agents used in leather footwear), In this photo, macerated, scaling lesions are visible between the 3rd and 4th interdigital spaces and extend to the subdigital skin of the foot. Image provided by Thomas Habif, MD. In this photo, chronic hyperkeratotic tinea pedis manifests as scaling and thickening of the soles that extends beyond the plantar surface in a moccasin distribution. Image provided by Thomas Habif, MD. © Springer Science+Business Media In this photo, onychomycosis is also visible. © Springer Science+Business Media © Springer Science+Business Media In this photo, scaling is visible in the interdigital space on close inspection. © Springer Science+Business Media In this photo, scaling and maceration are visible in the 4th interdigital space. © Springer Science+Business Media Chronic intertriginous tinea pedisis characterized by scaling, erythema, and erosion of the interdigital and subdigital skin of the feet, most commonly affecting the lateral 3 toes. Acute ulcerative tinea pedis(most often caused byT. mentagrophytesvar.interdigitale) typically begins in the 3rd and 4th interdigital spaces and extends to the lateral dorsum and/or the plantar surface of the arch. These toe web lesions are usually macerated and have scaling borders. Secondary bacterial infection, cellulitis, and lymphangitis are common complications. Vesiculobullous tinea pedis,in which vesicles develop on the soles and coalesce into bullae, is the less common result of a flare-up of interdigital tinea pedis; risk factors are occlusive shoes and environmental heat and humidity. 