Human infection caused by Exophiala pisciphila: case report and review

One year after receiving a liver transplant and 2 months after treatment with high doses of steroids and monoclonal anti-CD3 for an episode of rejection, a 38-year-old woman developed a skin papule above the left medial malleolus. The papule, which at first had an annular shape, evolved into a pustule, ulcerated, drained, and assumed a crusted verrucous appearance. Multiple satellite papules appeared around the lesion, which was incompletely excised and thought to represent squamous cell carcinoma. Review of the histologic slides revealed pseudoepitheliomatous hyperplasia with multiple epidermal and dermal abscesses, pigmented hyphae, and yeast-like forms. Culture of material obtained at reexcision yielded a dematiaceous fungus that was identified as Exophiala pisciphila. No evidence of dissemination was found. This represents a unique report of human infection with this fungus, a well-recognized pathogen of fish. Except for the absence of sclerotic bodies, the clinicopathologic features resembled those of chromoblastomycosis rather than those of the subcutaneous cystic form of phaeohyphomycosis often associated with species of Exophiala.