Teaching NeuroImages: Cerebral amyloid angiopathy–related inflammation presenting with isolated leptomeningitis

A 69-year-old woman presented with 1 month of rapid cognitive decline preceded by 1 year of very mild memory changes. Examination showed impaired attention, logopenic aphasia, anosognosia, simultagnosia, graphesthesia, and apraxia. Neuroimaging demonstrated leptomeningeal enhancement without significant parenchymal lesions or cerebral microbleeds (figure 1). A lymphocytic pleocytosis (15 nucleated cells/μL) was noted on CSF analysis. Extensive diagnostic testing was inconclusive, including flow cytometry and cytology, conventional angiography, body CT, and PET. Cerebral amyloid angiopathy–related inflammation (CAA-RI) was confirmed on brain biopsy (figure 2). CAA-RI rarely presents with isolated leptomeningeal enhancement and can be a challenging diagnosis.1,2