opportunistic infections caused by the dematiaceous (darkly pigmented) mitosporic fungi of alternaria, Bipolaris, cladosporium, Curvularia, and exophiala. These fungi have pigmented hyphae due to MELANIN in the cell wall. The initial subcutaneous cyst from the infection can become systemic and spread rapidly to renal, pulmonary and cerebral systems (see cerebral phaeohyphomycosis) in an immunocompromised host.