Tinea Pedis (Athlete's Foot)

Tinea pedis is the most common dermatophytosis Overview of Dermatophytoses Dermatophytoses are fungal infections of keratin in the skin and nails (nail infection is called tinea unguium or onychomycosis). Symptoms and signs vary by site of infection. Diagnosis is by... read more because moisture resulting from foot sweating facilitates fungal growth. Tinea pedis may occur as any of 4 clinical forms or in combination:

Chronic hyperkeratotic tinea pedis due to Trichophyton rubrum causes 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 Contact Dermatitis Contact dermatitis is inflammation of the skin caused by direct contact with irritants (irritant contact dermatitis) or allergens (allergic contact dermatitis). Symptoms include pruritus and... read more (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), irritant contact dermatitis Irritant contact dermatitis (ICD) Contact dermatitis is inflammation of the skin caused by direct contact with irritants (irritant contact dermatitis) or allergens (allergic contact dermatitis). Symptoms include pruritus and... read more , and psoriasis Psoriasis Psoriasis is an inflammatory disease that manifests most commonly as well-circumscribed, erythematous papules and plaques covered with silvery scales. Multiple factors contribute, including... read more .

Chronic intertriginous tinea pedis is 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 by T. mentagrophytes var. 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.