38-Year-Old With Foot Rash

Differential Diagnosis

• Allergic contact dermatitis
• Candidiasis
• Pitted keratolysis
• Tinea pedis

Diagnosis

The correct diagnosis in this case is tinea pedis, more commonly known as “athlete’s foot,” which is a localized, superficial fungal infection. The dermatophytes responsible for most cases of tinea pedis include Trichophyton rubrum, Trichophyton mentagrophytes, and Epidermophyton floccosum. The condition is more common in men and in athletes who use community showers in locker rooms and/or wear occlusive footwear that creates humid conditions around the foot.

What to Look For

• Tinea pedis has a varied clinical presentation but most often involves the web spaces and soles of the foot
• The rash may be asymptomatic or have varying degrees of pruritis
• Trichophyton rubrum may present with a red, scaly, moccasin-like plaque on the sole
• Interdigital cracking and maceration may be present and lead to secondary bacterial infection

Pearls for Urgent Care Management

• Consider performing a KOH (potassium hydroxide) evaluation for confirmation of the diagnosis
• Initial treatment should be with an antifungal agent with antidermatophyte activity
• Examples include azoles, allylamines, ciclopirox, butenafine, and tolnaftate

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