Snapshot A 50-year-old man presents to his primary care physician's office for a rash on his right foot. He reports that he has had this rash for several months intermittently. He also says the rash is associated with occasional itchiness and a burning sensation. He admits that he often wears heavy-duty boots because of his profession as a construction worker, and he does not take them off until bedtime. On physical exam, there is diffuse erythema and thick scaling over the plantar surface and macerations in the space between the toes. He is prescribed an antifungal topical cream. Introduction Clinical definition a dermatophytosis tinea pedis login to view 2 more bullets tinea manuum login to view 1 more bullet 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 dermatophytes Trichophyton login to view 1 more bullet Microsporum Epidermophyton Pathogenesis fungus infects superficial keratinized tissue limited to stratum corneum, hair, or nails dermatophytes require keratin to grow Associated conditions tinea cruris onychomycosis Prognosis responsive to topical treatment Presentation Symptoms primary symptoms itch burning especially between the toes or fingers sloughing of skin on feet Physical exam erythema and overlying scaling 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 login to view 1 more bullet drugs login to view 5 more bullets oral therapy indications login to view 2 more bullets drugs login to view 2 more bullets 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