Cerebral Phaeohyphomycosis Caused by Exophiala dermatitidis in a Chinese CARD9-Deficient Patient: A Case Report and Literature Review

Abstract

<i>Exophiala dermatitidis</i>, a dematiaceous fungus typically found in decaying organic matter worldwide, is a rare cause of fungal infections. Cerebral phaeohyphomycosis is a sporadic but often fatal infection of the brain caused by <i>E. dermatitidis</i>. However, due to limited reports, little is known about its specific predisposing factors, clinical manifestation, and optimal treatment modality. Here, we report a clinical presentation and management of cerebral phaeohyphomycosis in a Chinese patient. An otherwise healthy, young male who was diagnosed with neck fungal lymphadenitis caused by <i>E. dermatitidis</i> 7 months prior and was treated with itraconazole, presented later with progressive intracranial hypertension and persistent coma. Culture of the neck lymphoid tissue produced growth of a black yeast-like fungus, which was identified as <i>E. dermatitidis</i> by sequencing of the ribosomal DNA internal transcribed spacer (ITS) domains. Accordingly, a cerebral biopsy was performed, and the pathological report showed mycelia and fungal granulomas. We also sequenced <i>CARD9</i> in the patient and found him to be homozygous for loss-of-function mutation; his parents were heterozygous for the same mutation. This is a first case report of cerebral phaeohyphomycosis caused by <i>E. dermatitidis</i> in a <i>CARD9</i>-deficient Chinese patient. He eventually succumbed to brain herniation and severe lung infection with a poor response to therapy. Thus, previously healthy patients with unexplained invasive <i>E. dermatitidis</i> infection, at any age, should be tested for inherited <i>CARD9</i> deficiency.