A 35-year-old male with ankylosing spondylitis complained of refractory and recurrent headaches, confusion, and word-finding difficulties for 2 weeks duration. Symptoms began after the infliximab infusion, which he has been receiving for 2 years, was changed to a biosimilar product. Initial routine testing and MRI brain with/without contrast were unremarkable. He was treated for migraines including a 4-day course of steroids. However, the symptoms worsened. On presentation, the physical examination revealed inattentiveness, difficulty recognizing familiar faces, impaired calculations, and decreased fluency. EEG demonstrated moderate generalized background slowing with frequent runs of generalized rhythmic delta activity. Laboratory testing showed slightly elevated ESR (24 mm/h) and CRP (2.8 mg/dL). CSF was significant for WBC 174 cells/mcL, protein 133.4 mg/dL, ACE 4.6 U/L, CD4:CD8 ratio 3:1. CT chest, abdomen and pelvis demonstrated diffuse lymphadenopathy. Repeat MRI brain demonstrated leptomeningeal enhancement most pronounced in the bilateral posterior temporal and occipital lobes. CT facial bones with contrast described increased density with central enhancement of the right maxillary sinus. Biopsy of a left inguinal lymph node revealed noncaseating granulomas consistent with sarcoid. Treatment with prednisone resulted in significant clinical improvement and resolution of leptomeningeal enhancement at 1 month. These findings are suggestive of neurosarcoidosis with possible involvement of the leptomeninges, sinuses and lymph nodes.