Abstract Number: Esoc2026a213 Granulomatous Angiitis: A Rare Form of Primary CNS Vasculitis

Abstract Background and aims Granulomatous angiitis is a rare form of vasculitis affecting small and medium sized vessels. It presents with multifocal neurologic symptoms including encephalopathy, headache and stroke. Methods We highlight a case of a 70-year-old Caucasian male with hypertension who was first evaluated in March 2024 for two days of expressive aphasia. At that time CT scan of the head revealed left frontal intraparenchymal and diffuse subarachnoid hemorrhage. Cerebral diagnostic angiogram (DSA) was normal. He was lost to follow up but was readmitted in September 2025 for thunderclap headache. This time CT scan revealed new supratentorial subarachnoid hemorrhage. DSA performed was again unremarkable. A diagnosis of probable amyloid angiopathy was made. A month later the patient presented with progressive decline in mental status and left hemiparesis. His NIHSS was 22. Results MRI of the brain with gadolinium revealed several bilateral punctate cerebral infarcts, leptomeningeal enhancement and superficial siderosis. Lumbar puncture done resulted in 493/mm3 nucleated cells, 86 mg/dl proteins. CSF viral studies and malignant cells were negative. Comprehensive work-up was undertaken to rule out secondary causes. Subsequent brain biopsy showed multinucleated giant cells and mural macrophages consistent with granulomatous angiitis. Leptomeningeal inflamed vessel was not notable for amyloid. Treatment consisting of high intensity steroid followed by intravenous cyclophosphamide was initiated. Conclusions In summary, primary angiitis of the central nervous system has protean manifestation. A high index of suspicion is necessary for correct diagnosis, treatment and outcome. Conflict of interest Marilou Ching: nothing to disclose