1. This 38-year-old male presented with severe frontal headache, speech difficulties, weakness, and confusion. Imaging showed multiple small white matter lesions that progressed significantly over 4 days.
2. Cerebrospinal fluid analysis showed elevated white blood cells and protein with positive oligoclonal bands. Infectious and autoimmune workups were negative.
3. Brain biopsy showed early acute ischemic changes and a microscopic focus of acute infarction without evidence of vasculitis, inflammation, or other pathologies. This is consistent with a diagnosis of primary central nervous system vasculitis.