A case of immunocompetent intracranial cryptococcoma in which intraoperative rapid pathological diagnosis and polymerase chain reaction led to early treatment: What to know to avoid misdiagnosis as brain tumor

Background: Cryptococcal infections of the central nervous system are infrequent in immunocompetent hosts and usually present as meningitis. However, a fungal mass called a cryptococcoma may form, requiring caution in therapeutic intervention. Here, we report a rare case in which treatment of intraventricular cryptococcoma in an immunocompetent patient was facilitated by rapid pathological diagnosis.

Case description: A 58-year-old previously healthy man was admitted to our hospital with fever, headache, and gradually worsening hearing loss over 1 month. Cerebrospinal fluid analysis showed moderately elevated levels of protein and lymphocytic cells and decreased glucose. In addition, β2-microglobulin was highly elevated. Magnetic resonance imaging showed homogeneously enhanced lesions in lateral ventricles of the left and right hemispheres and the subarachnoid space, and ¹⁸F-fluorodeoxyglucose positron emission tomography revealed abnormal uptake corresponding to the lesion. A surgical excision was performed to achieve a definitive diagnosis. Intraoperative rapid pathology, including immunohistochemistry (IHC), yielded negative results for malignant tumor, suggesting the possibility of inflammatory granuloma. Additional targeted pathological diagnosis was immediately performed. Paraffin-embedded histopathological examination showed fibrocaseous granuloma and numerous fungal spores. Cryptococcus neoformans within the granuloma were suggested by Fontana-Masson and Grocott staining and confirmed by polymerase chain reaction (PCR), leading to a diagnosis of cryptococcoma. Antifungal agents were started 3 days postoperatively. The patient has since been doing well, with no recurrence.

Conclusion: This pathology can be difficult to distinguish from a brain tumor, so early pathological diagnosis, including rapid pathology with IHC and PCR, may be crucial.