Intraventricular black fungal hyphal masses caused by Cladophialophora bantiana: illustrative case

Abstract

BACKGROUND CNS fungal infections are rare, life-threatening conditions primarily affecting immunocompromised hosts. While they typically present as brain abscesses, intraventricular proliferation of fungal hyphae is exceedingly rare, and its neuroendoscopic findings have seldom been reported. OBSERVATIONS A man in his 80s with a history of malignancies presented with a 1-month history of headache. Brain MRI showed contrast-enhancing lesions along the genu of corpus callosum and lateral ventricles, as well as a nonenhancing lesion protruding into the ventricles. Although these findings were atypical, an endoscopic biopsy was performed because the lesions showed a tendency to enlarge, raising suspicion of a malignant tumor. Neuroendoscopic examination revealed a black-pigmented intraventricular fungal mass, which was partially resected. Shotgun metagenomic analysis identified the pathogen as Cladophialophora bantiana. LESSONS C. bantiana exhibits marked neurotropism and is known to cause CNS fungal infections even in immunocompetent individuals. Although intraventricular extension of phaeohyphomycosis is extremely rare and preoperative differential diagnosis remains challenging, a nonenhancing lesion protruding into the ventricles was considered to reflect the presence of fungal hyphae in this case. https://thejns.org/doi/10.3171/CASE26730