Use Primary Central Nervous System Vasculitis to guide the working diagnosis and next step; let the main risk or management issue drive escalation, treatment choice, and follow-up.

Full-thickness brain and meningeal biopsy remains the absolute gold standard for a definitive diagnosis.; Two hallmark conditions are granulomatosis with polyangiitis and microscopic polyangiitis.; Standard catheter-based cerebral angiography is simply not reliable on its own because it fails to visualize the microscopic, small vessels that this disease typically targets.; Your primary objective must be to completely rule out any systemic autoimmune diseases or infectious mimics.; They are actually not helpful at all.