Chromoblastomycosis caused by a meristematic mutant of Fonsecaea monophora.

We report the first case of chromoblastomycosis caused by a meristematic mutant of Fonsecaea monophora in an 81-year-old Cantonese male. The patient had a seven-month history of a red plaque with thick yellow crust and purulent exudates on the back of his right hand. Microscopic examination of direct smears revealed brown sclerotic cells and black colonies were recovered in culture from samples of the purulent exudantes. The microscopic appearance of this isolate was quite different from that of other Fonsecaea species, exhibiting mere meristematic growth. The rDNA ITS sequence data confirmed that this isolate was a mutant of Fonsecaea monophora. The patient showed good response to treatment with itraconazole and complete healing was achieved without relapse after long-term follow-up.