Giant Posterior Fossa Tuberculoma Mimicking Atypical Teratoid/Rhabdoid Tumor in a Child: Illustrative Case.

Abstract

Intracranial tuberculomas are rare manifestations of extrapulmonary tuberculosis that can closely mimic malignant posterior fossa tumors in children, particularly in tuberculosis-endemic regions. The radiological and clinical overlap with aggressive neoplasms such as atypical teratoid/rhabdoid tumor (AT/RT) poses a significant diagnostic challenge. A 5-year-old immunocompetent boy presented with progressive headache and irritability. Magnetic resonance imaging (MRI) of the brain revealed a large (45 × 38 mm) lesion in the cerebellar vermis and left hemisphere with mass effect on the fourth ventricle and brainstem, causing obstructive hydrocephalus. A ventriculoperitoneal (VPMP) shunt was placed for hydrocephalus management. Subsequently, left suboccipital craniectomy with tumor decompression was performed. Intraoperative crush biopsy was initially reported as atypical rhabdoid tumor. However, final histopathological examination revealed extensive granulomatous inflammation with epithelioid cell granuloma, Langhans-type giant cells, and macrophages. Immunohistochemistry showed CD68 positivity (confirming macrophagic nature), EMA negativity (ruling out meningothelial tumor), and vimentin positivity in fibrotic tissue. Acid-fast bacilli (AFB) staining was positive. The final impression was chronic granulomatous pathology consistent with tuberculosis. This case underscores the importance of maintaining a high index of suspicion for CNS tuberculoma in the differential diagnosis of posterior fossa space-occupying lesions in children, particularly in endemic regions. Intraoperative crush biopsy may be misleading, and definitive histopathological examination with special stains is essential to avoid misdiagnosis and inappropriate treatment. Early confirmation of tuberculosis can dramatically alter management from aggressive oncological therapy to curative antitubercular treatment.