2026 American Academy of Neurology Abstract Website

Objective:

To enhance clinician awareness of the atypical and tumor-mimicking presentations of tumefactive cerebral amyloid angiopathy, thereby improving diagnostic precision and guiding evidence-based management

Background:

Cerebral amyloid angiopathy is a progressive small vessel disease marked by amyloid-β deposition in cortical and leptomeningeal vessels, causing fragility with predisposition to lobar hemorrhages. A rare variant, inflammatory CAA (<1/100,000), reflects an autoimmune response to vascular Aβ, presenting with encephalopathy, seizures, or focal deficits, often mimicking neoplasms on neuroimaging but responsive to immunosuppression.

Design/Methods:

Case-report

Results:

A 65-year-old Caucasian-male with history of atrial fibrillation post-ablation, hypertension, and a left parietal mass biopsied in 2016 (inconclusive inflammatory/reactive lesion, without amyloid staining), presented for seizure management. The examination revealed impaired remote memory, word-finding difficulty and frontal lobe signs. Labs showed positive ANA (1:1280), normal cerebrospinal fluid (CSF) cell count, mildly elevated protein 48 mg/dL (15-45), and negative infectious, inflammatory, paraneoplastic, autoimmune encephalopathy, and JC virus panels. Non-contrast Computed Tomography of the head showed multifocal vasogenic edema in the bilateral frontal and left parietal lobes, while vessel imaging was unremarkable. Magnetic resonance imaging of the brain demonstrated asymmetrical spotty and confluent bilateral hyperintensities (left > right) and innumerable cortical/cortico-subcortical microbleeds on susceptibility-weighted imaging, most prominent in the left frontal and parietal lobes. On neurology review, findings suggestive of probable CAA-related inflammation (CAA-RI) and a left frontal lobe biopsy confirmed the cerebral amyloid angiopathy on amyloid staining with focal perivascular lymphocytic inflammation and gliosis. The patient was treated with intravenous methylprednisolone (1 g daily ×3 days), followed by a 12-week taper.

Conclusions:

This example illustrates that tumefactive Cerebral Amyloid Angiopathy can present atypically with subacute/chronic cognitive decline and seizures while mimicking low grade CNS Neoplasm. However, neuroradiologic images can be non-specific, prompting the need for invasive techniques such as biopsy, highlighting the importance of early recognition in managing this rare entity.