Isolated Central Nervous System Tuberculosis Presenting as Progressive Encephalopathy: A Report of a Biopsy-Proven Case.

Central nervous system (CNS) tuberculosis (TB) is an uncommon but severe manifestation of Mycobacterium tuberculosis infection and is associated with significant morbidity and mortality. Its clinical and radiologic presentations are often nonspecific and may mimic malignancy, inflammatory disorders, or fungal infections, frequently resulting in diagnostic delay. Conventional cerebrospinal fluid (CSF) testing has limited sensitivity, and definitive diagnosis may require histopathologic confirmation when noninvasive studies are inconclusive. We report the case of a 76-year-old woman with a history of cerebrovascular accident and hypertension who presented with a six-month history of progressive encephalopathy following travel to Ghana. Initial neuroimaging was unrevealing, while CSF analysis demonstrated lymphocytic pleocytosis with markedly low glucose; routine meningitis testing was negative. Subsequent brain magnetic resonance imaging (MRI) revealed diffuse nodular leptomeningeal enhancement involving the posterior fossa and brainstem. Given high clinical suspicion, empiric antituberculous therapy was initiated. Definitive diagnosis was achieved through open meningeal biopsy, which demonstrated necrotizing granulomas with acid-fast bacilli, confirming CNS TB. No evidence of pulmonary TB was identified. The patient demonstrated significant clinical and radiologic improvement with continued antituberculous therapy and adjunctive corticosteroids. This case highlights the diagnostic complexity of CNS TB and emphasizes the importance of histopathologic confirmation when noninvasive testing is nondiagnostic. Early recognition of CNS TB in patients with chronic meningitis, atypical neuroimaging findings, and relevant epidemiologic exposure is critical for timely treatment and improved neurologic outcomes.