Primary angiitis of the central nervous system (PACNS) is a rare disorder. However, it is often considered in the differential diagnosis of vascular or inflammatory CNS diseases. Diagnosis is challenging, as specific biomarkers are lacking and the clinical presentation can be variable. A definitive diagnosis can only be established by biopsy of the inflammatory changes in the vascular wall. Alternatively, the diagnosis of PACNS can also be based on the synopsis of clinical, radiological, and laboratory findings. Different subtypes of PACNS have been described in recent years, depending on the size of the affected vessels or histopathological patterns. Based on selective literature research in the database PubMed on the subject of CNS vasculitis, this article reviews the diagnostic characteristics and differential diagnosis of the condition. We suggest a diagnostic algorithm customized to the size of the affected vessels. Lastly, therapeutic options and the outcome of PACNS are briefly outlined.
