A 14-year-old boy presented to our institution with a 1-month history of neurocognitive decline and intermittent fevers. His history was significant for fevers, headaches, and a 10-lb weight loss. Previous examinations by multiple medical providers were significant only for bilateral cervical lymphadenopathy. Previous laboratory workup revealed leukopenia, neutropenia, and elevated inflammatory markers. Despite improvement in his laboratory values after his initial presentation, his fevers persisted, and he developed slowed and “jerky” movements, increased sleep, slurred speech, delusions, visual hallucinations, and deterioration in his school performance. A brain MRI performed at an outside hospital before admission at our institution was concerning for patchy, increased T2 and fluid-attenuated inversion recovery signal intensity in multiple areas, including the basal ganglia. After transfer to our institution and admission to the pediatric hospital medicine team, the patient had an acute decompensation. Our subspecialists will discuss the initial evaluation, workup, differential diagnosis, definitive diagnosis, and subsequent management of this patient.