Primary Small Vessel Central Nervous System Vasculitis Presenting as a Parietotemporal Mass: A Case Report

Introduction: Primary central nervous system vasculitis (PCNSV) of small vessels is an exceedingly rare presentation of vasculitis. Diagnosis typically takes many months, requires multiple diagnostic modalities, and includes a positive biopsy in less than 50% of cases. We present a unique case of PCNSV that will help clinicians identify this rare disease. Clinical Findings: A man in his 60s presented with confusion and aphasia and was found to have a parietotemporal brain mass. The mass was heterogenous, with inflammatory, cystic, necrotic, and hemorrhagic components. Two separate brain biopsies underwent review at 3 institutions before the diagnosis was made. Clinical Course: The patient was initially treated with steroids, amphotericin B, and flucytosine due to concern for cryptococcus on initial biopsy. After a negative universal polymerase chain reaction and repeat biopsy, he was treated with prednisone, cyclophosphamide, and methotrexate without significant improvement. He died in hospice 4 months after initial presentation. Conclusions: Diagnosing PCNSV can be extremely difficult due to sampling error in biopsy tissue and a lack of systemic markers. We review PCNSV and its epidemiology, diagnosis, and treatment.