A 35-year-old woman with a history of unicentric form of Castleman’s Disease (hyaline vascular subtype) and interstitial lung disease presented with sudden-onset dysarthria and left-sided weakness. CT Angiogram (CTA) of the head and neck revealed focal high-grade stenosis of the right M1 segment of the middle cerebral artery (MCA). MRI Brain showed acute infarcts in the right caudate head, lentiform nucleus, and right parietal lobe. Black blood imaging of intracranial vessels revealed multifocal, heterogeneous enhancement of the right M1 suggesting an underlying inflammatory vasculopathy. Despite extensive workup, including tests for atherosclerotic risk factors, the etiology of the high-grade stenosis remained unclear. The patient experienced near-complete resolution of hemiparesis and was discharged on dual antiplatelet therapy and atorvastatin. Two months later, repeat black blood imaging of intracranial vessels showed resolution of right M1 enhancement.

Four months later, she presented again with acute encephalopathy and left-sided weakness. A head CT revealed a new hypodensity in the right ACA territory, with CTA showing a right distal ACA cutoff and chronic right M1 occlusion. Despite a thorough stroke workup, including transesophageal echocardiogram (TEE) and an implantable loop recorder, the cause of her recurrent strokes was elusive. She was again discharged on dual antiplatelet therapy.