Snapshot A 40-year-old woman presentsto her dermatologist for a rash on her foot. She reports that this has been going on for about 2 weeks now ever since she started walking around her home barefoot. Her foot is pruritic and has caused her to continuously scratch the affected area. Physical exam reveals erythema, scales, and macerations on her left foot. There are similar findings on her right hand. She is prescribed an antifungal cream for treatment of both her hand and foot rash. Introduction Clinical definition a dermatophytosis tinea pedis superficial fungal skin infection of the foot also known as athlete’s foot tinea manuum superficial fungal skin infection of the hand Associated conditions tinea cruris onychomycosis Epidemiology Prevalence 2.9% prevalence Demographics adults > children males > females Risk factors moist and warm environment occlusive footwear soldiers hyperhidrosis broken skin walking barefoot Etiology Pathogenesis fungus infects superficial keratinized tissue limited to stratum corneum, hair, or nails dermatophytes require keratin to grow Dermatophytes Trichophyton most commonly Trichophyton rubrum and Trichophyton interdigitale Microsporum Epidermophyton Presentation Symptoms primary symptoms itch and/or burning especially between the toes or fingers sloughing of skin on feet Physical exam erythema and overlying scale fissures and macerations, especially of the feet typically in interdigital spaces and plantar surface vesicles may also be seen Studies KOH preparation skin scrapings at active edge of lesion mixed with KOH presence of septated hyphae and spores indicates fungal infection Diagnostic criteria diagnosis usually based on clinical history and physical exam Differential Contact dermatitis Psoriasis Treatment Medical topical therapy indication localized lesions drugs terbinafine 1% approved for patients 12 years of age and older clotrimazole 1% approved for patients 2 years of age and older ketoconazole 2% oral therapy indications widespread disease concomitant onychomycosis drugs terbinafine itraconazole Complications Id reaction (dermatophytid reaction) secondary immunological reaction at a separate site on the skin caused by activated circulating antibodies or activated T-cells Secondary bacterial infection Prognosis responsive to topical treatment