Doubly Misdiagnosed: Exophiala Masquerading as Squamous Cell Carcinoma and Chromoblastomycosis

Deep cutaneous fungal infections (DCFI) can arise in the setting of skin trauma and immunosuppression. DCFI may be secondary to chromoblastomycosis, which is typically characterized by pseudoepitheliomatous hyperplasia histologically and can be mistaken for squamous cell carcinoma. In addition, copper penny spore-like pigmented yeast forms on Grocott's methenamine silver stain can suggest chromoblastomycosis, but this finding is not specific. By contrast, phaeohyphomycosis characteristically exhibits circumscribed pseudocyst or abscess on histopathology, and both yeast and hyphae can be seen. Our case reports a DCFI with pseudoepitheliomatous hyperplasia and copper penny yeast forms, ultimately diagnosed as phaeohyphomycosis after isolating Exophiala spinifera on fungal culture.

Automated summary

Deep cutaneous fungal infections (DCFI) can occur in cases of skin trauma and immunosuppression. Chromoblastomycosis is often characterized by pseudoepitheliomatous hyperplasia histologically, which can be mistaken for squamous cell carcinoma. Phaeohyphomycosis, on the other hand, exhibits circumscribed pseudocysts or abscesses on histopathology.