Diagnostic dilemma in CNS vasculitis: a case of primary angiitis of central nervous system mimicking anti-neutrophilic cytoplasmic antibody-associated vasculitis

Abstract

Authors present a diagnostically challenging case of Central Nervous System (CNS) vasculitis presenting with aphasia, confusion, and right-sided weakness due to cerebral vascular accident, initially suspected to be Anti-Neutrophilic Cytoplasmic Antibody (ANCA)-associated vasculitis due to elevated PR3 ANCA titers. The work up for lupus and anti-phospholipid antibodies was negative. Magnetic Resonance Imaging of brain demonstrated abnormal T2 FLAIR and diffusion-weighted imaging with patchy, enhancing lesions, progression of middle cerebral artery involvement, and subacute infarcts in the left parietal and occipital lobes. He responded to Intravenous methylprednisolone followed by oral prednisone and Rituximab infusions every 6 months. Inspite of this, his disease progressed as he developed recurrent headaches, transient ischemic attacks, seizures, paranoia, altered mental status, and agitation. His repeat ANCA test came back negative. Due to the absence of systemic features and subsequent negative ANCA result, his diagnosis was revised to Primary Angiitis of the CNS (PACNS). Treatment with daily oral cyclophosphamide in a dose of 2 mg per kg body weight resulted in disease stabilization and clinical improvement.