Chromoblastomycosis is a neglected fungal infection that involves the epidermis and subcutaneous tissue. It predominates in tropical areas and occurs after the traumatic inoculation of environmental dematiaceous filamentous fungi. A recent report describes a case of an immunosuppressed patient who was diagnosed with foot chromoblastomycosis due to an uncommon dematiaceous fungus. The patient was a 52-year-old Congolese kidney transplant woman who presented with a painful lesion on her foot. She reported no trauma to the lower limbs during the previous months. She resided in France and had not returned to the Congo for 8 years. 

Her skin histology and mycological examination revealed swollen dark filaments associated with dematiaceous muriform cells, pathognomonic of chromoblastomycosis. Cultures grew with darkly pigmented colonies, yielding poor microscopic features. The phylogenetic analysis confirmed the isolate to be a member of Kirschsteiniotheliales (Dothideomycetes) and unrelated to the Chaetotyriales, the most commonly described species for chromoblastomycosis. 

No bone spreading prompted excision surgery of the entire lesion, followed by liposomal amphotericin B therapy. The therapy resulted in complete healing after 6 months. 

As illustrated by this case, various dematiaceous fungi from the environment have the potential to cause phaeohyphomycosis, particularly chromoblastomycosis. Thus clinicians must send every sample to mycology labs for appropriate diagnosis.

Source: Guegan H, Cailleaux M, Le Gall F, et al. Chromoblastomycosis due to a never-before-seen dematiaceous fungus in a kidney transplant patient. Microorganisms. 2021;9(10):2139.