Chromoblastomycosis due to a never-before-seen dematiaceous fungus in a kidney transplant patient

Abstract

Chromoblastomycosis is a neglected fungal infection of the epidermis and subcutaneous tissue that predominates in tropical areas and results from the traumatic inoculation of environmental dematiaceous filamentous fungi. We describe the case of an immunosuppressed patient diagnosed with foot chromoblastomycosis due to an uncommon dematiaceous fungus. A 52-year-old Congolese kidney transplant woman presented with a painful lesion located on the foot. No trauma to the lower limbs was reported during the previous months. She lived in France and had not returned to the Congo over the previous eight years. Histology and mycological examination from skin biopsy revealed swollen dark filaments associated with dematiaceous muriform cells, pathognomonic of chromoblastomycosis. Cultures grew with dark pigmented colonies, yielding poor microscopic features. The phylogenetic analysis confirmed that the isolate was a member of Kirschsteiniotheliales (Dothideomycetes) and unrelated to the Chaetotyriales, of which most species commonly responsible for chromoblastomycosis belong. As there was no bone spreading, excision surgery of the entire lesion followed by liposomal amphotericin B therapy resulted in complete healing after six months. This original case illustrates the potential diversity of environmental dematiaceous fungi responsible for phaeohyphomycosis, especially chromoblastomycosis, and the need to send samples to mycology labs for appropriate diagnosis.