Tinea incognito in Italy: a 15-year survey.

Tinea incognito or steroid modified tinea is a dermatophytic infection in which topical or systemic steroids, administered as a result of dermatological misdiagnosis or preexisting pathologies, have modified the clinical appearance of the fungal infection, transforming the typical ringworm and mimicking other skin diseases. This is a retrospective study of the agents, clinical aspects, sources of infection of 200 cases (98 males, 102 females, mean age 42 years) of tinea incognito, observed in Siena and Milan, Italy, in the period 1987-2002. In order of decreasing frequency, Trichophyton rubrum, Trichophyton mentagrophytes, Epidermophyton floccosum, Microsporum canis, Microsporum gypseum, Trichophyton violaceum and Trichophyton erinacei were isolated. The clinical appearance of the infection was lupus erythematosus discoid-like, eczema-like, rosacea-like, especially on the face, impetigo-like and eczema-like on trunk and limbs. Less often the dermatophytosis resembled psoriasis, purpura, seborrhoic dermatitis and lichen planus. There was folliculitis in 9% of cases and dermatophytid in 3% of cases. Antimycotic therapy brought about clinical and mycological recovery in all patients except one, who had iatrogenic immunodepression.