Dermatophytosis (Tinea) That Resembles Necrobiosis Lipoidica

A 52-year-old man was annoyed by a solitary itchy patch on his anterior foreleg. He was in good health except for type 2 diabetes mellitus and mild hypertension.

Key point: The plaque looks similar to and should suggest necrobiosis lipoidica because of its shape and location. However, unlike the latter, this lesion is surmounted by significant scale formation. A KOH preparation was positive, which verified the presumptive diagnosis of dermatophytosis (tinea).

Treatment: Application of 2% naftifine cream once daily for 2 weeks led to resolution of the fungal infection. The patient refused treatment for his obvious onychomycosis.

Note: Always check the toenails for fungal infection after diagnosing tinea pedis, corporis, or cruris. The toenails may act as the source of infection and a reservoir, which may lead to reinfection after the cutaneous dermatophytosis is cleared.