Isolated cerebellopontine angle neurosarcoidosis mimicking meningioma: a diagnostic pitfall. Illustrative case.

BACKGROUND: Neurosarcoidosis (NS) is a rare inflammatory disease that can mimic intracranial neoplasms. Its presentation as an isolated cerebellopontine angle (CPA) mass is exceedingly uncommon and typically resembles vestibular schwannomas or meningiomas, complicating the diagnostic process. OBSERVATIONS: A 25-year-old man presented with progressive diplopia and hearing loss. MRI revealed a diffusely enhancing lesion in the left CPA. Because the initial workup was inconclusive and intraoperative pathology heavily favored a nonneoplastic inflammatory process, subtotal resection was performed. Histopathological examination revealed a histiocyte-rich inflammatory infiltration with occasional multinucleated giant cells. The patient was treated with high-dose corticosteroids and experienced a good recovery. LESSONS: This case underscores the importance of including NS in the differential diagnosis of CPA tumors, particularly in young patients with atypical features. Early consideration and histopathological confirmation are crucial to avoid unnecessary extensive resection and to enable timely initiation of appropriate medical therapy. https://thejns.org/doi/10.3171/CASE2668.