Answer to May 2016 Photo Quiz

Answer: Chromoblastomycosis. The melanized elements shown in the photo quiz are muriform cells that can be considered the hallmark of chromoblastomycosis. These fungal structures, which divide by internal septation and are sometimes referred to as “sclerotic” or “fumagoid” cells, “copper pennies,” or “medlar bodies,” were first described in 1915 (1). Muriform cells can be easily visualized after preparation of skin scrapings with potassium hydroxide or, as with our patient, within granulomas along with giant cells after histopathological examination of a skin biopsy specimen. Clinicians, microbiologists, and histopathologists should therefore be aware that the recovery of these structures in clinical specimens allows for diagnosis of chromoblastomycosis and should prompt initiation of therapy. A few days after these cells were identified in our patient, mycological cultures on Sabouraud's dextrose agar grew a dematiaceous fungus identified as a Fonsecaea species (2). Definitive identification of Fonsecaea monophora was eventually obtained by sequencing of the internal transcribed spacer (ITS) region of ribosomal DNA (rDNA). Once the diagnosis was made, two stages of liquid nitrogen cryotherapy were applied. In the absence of significant clinical improvement, the patient was finally switched to oral voriconazole (200 mg twice a day). In March 2013, after 3 months of voriconazole therapy, a significant regression of the lesion was noted and the control biopsy specimen was negative on both direct examination and mycological culture.