Neurosarcoidosis: When Altered Mental Status Is a Sign of Systemic Disease.

Sarcoidosis is a systemic granulomatous disease of unknown etiology, characterized by a heterogeneous clinical course and the potential to affect any organ. Neurological involvement is rare and often mimics other nervous system disorders, with diagnosis based on the correlation of clinical, radiological, and histological findings, and biopsy of a suspected lesion serving as the definitive diagnostic method. We report the case of a 59-year-old woman, previously independent, who presented with progressive cognitive decline over 4-5 weeks, culminating in the inability to perform basic activities. Based on clinical, laboratory, and imaging findings, including magnetic resonance imaging and FDG-PET, a diagnosis of neurosarcoidosis (NS) was established, and oral corticosteroid therapy was initiated, resulting in significant clinical and imaging improvement. Although histological confirmation was not obtained, the integration of clinical and imaging findings provided consistent support for the diagnosis. This case highlights the importance of early recognition of NS, particularly in subacute presentations with cognitive impairment.