Cutaneous phaeohyphomycosis due to Alternaria tenuissima.

A 50-year-old gardener with a 3-year history of pemphigus vulgaris and steroid-induced diabetes complained of various papulonodular lesions on the left elbow. The lesions had appeared 11 months previously. Skin biopsy showed chronic granulomatous inflammation of the dermis which contained septate hyphae and large spores mainly free. Fragments of the biopsy specimen, cultured on Sabouraud glucose agar without cycloheximide, for 4 days, produced soft white colonies which later turned blackish brown, especially on the underside. On the basis of the microscopic characters of the conidiophores and conidia, Alternaria tenuissima was identified. This phaeohyphomycete has only been isolated previously in two other cases in Italy.