A Diagnostic Dilemma: A Case of Neurosarcoidosis Without Systemic Sarcoidosis.

Sarcoidosis is a multisystem granulomatous disorder of unknown etiology characterized by non-caseating granulomas in involved organs. Approximately 10% of patients with sarcoidosis exhibit central nervous system involvement. However, the occurrence of isolated neurosarcoidosis without concurrent systemic signs is very rare, affecting less than 1% of patients. We report a case of isolated neurosarcoidosis in a previously healthy patient who initially presented with a single episode of seizure and loss of consciousness. Brain MRI showed T2/fluid-attenuated inversion recovery (FLAIR) hyperintense extra-axial soft tissue mass over the left cerebral convexity measuring approximately 14 mm in maximum depth. Excisional biopsy of the brain mass showed chronic non-caseating granulomatous inflammation with epitheloid cells that was consistent with sarcoidosis. Treatment with high dose-steroids led to significant clinical improvement. At a two-year follow-up, there were no signs of systemic disease or recurrence of the meningeal mass. This case emphasizes the rarity of such presentation, diagnostic difficulties, and the importance of high suspicion and timely management to prevent debilitating neurologic complications.