Pityrosporum Folliculitis: Its Potential for Confusion with Skin Lesions of Systemic Candidiasis

Development of an erythematous, papulonodular to papulopustular skin eruption in four febrile, immunocompromised patients raised the possibility of a systemic mycosis when Gram's stains of unroofed lesions disclosed budding yeasts. Candidiasis, torulopsosis, sporotrichosis, and cryptococcosis were considered in the differential diagnosis, and therapy with amphotericin B was begun. Skin biopsy specimens disclosed fungi to be located exclusively within intact and ruptured hair follicles. Inability of the fungi to grow on media that were not supplemented with lipid and their structure and location all suggested the presence of Pityrosporum sp. When hematogenous dissemination of a mycosis to the skin is suspected, the diagnosis must be based on biopsy specimen demonstration of dermal invasion, ideally with positive cultures. Pityrosporum sp, common skin saprophytes, may produce folliculitis, and be mistaken for pathogenic yeasts.