Cerebral phaeohyphomycosis caused by Xylohypha bantiana,with a review of the literature

A 76-year-old male with chief complaints of back and right leg sciatica was hospitalized. His abdominal CT scan revealed lumber spondylitic stenosis. A laminectomy was performed. Postoperatively, he became febrile, aphasic and had grand mal seizure. A left craniotomy of the front abscess, seen in the CT scan, was performed. H and E stained smears of drainage revealed dematiaceous, septate hyphae. Cultures of the abscess drainage grew an olivaceous-grey fungus. Based on macro- and micro-morphological characters, growth at 42° C, and exoantigenic analysis, the patient's fungus was identified as Xylohypha bantiana. Treatment with amphotericin B and 5-fluorocytosine was initiated. Despite surgical procedures and antifungal therapy, the patient's condition deteriorated and he died a few weeks later due to cerebral edema. The case reported here is the first microscopically, culturally, histopathologically and exoantigenically proven case of phaeohyphomycosis caused by X. bantiana in the province of Alberta and from Canada. A review of the literature on cases of X. bantiana infections has also been presented.     

The medically important dematiaceous fungi and their identification

Dematiaceous fungi include a large group of organisms that are darkly pigmented (dark brown, olivaceous, or black). In most cases the pigment is melanin, and specifically, dihydroxynaphthalene melanin. The diseases produced include chromoblastomycosis, eumycotic mycetoma, and phaeohyphomycosis. Phaeohyphomycosis is a new classification for a diverse group of previously known entities grouped together on the basis of finding dematiaceous hyphal and/or yeast-like forms in tissue; tissue involvement may be superficial, cutaneous and corneal, subcutaneous, or systemic. Identification of these fungi is based mostly upon morphology. Important structures include annellides (Phaeoannellomyces, Exophiala), phialides (Phialophora, Wangiella), adelophialides (Phialemonium without collarettes, Lecythophora with collarettes), differentiation of conidiophores (Xylohypha versus Cladosporium) and conidial hilum, septation and germination (Bipolaris, Drechslera, Exserohilum). Useful laboratory tests include the 12% gelatin test (controversial), nitrate assimilation (W. dermatitidis is negative, most other species are positive), and determination of temperature maxima (especially 37 degrees C for E. jeanselmei, 40 degrees C for W. dermatitidis and B. spicifera, 42 degrees C for X. bantiana, and 45 degrees C for Dactylaria constricta var. gallopava and Scedosporium inflatum).