Patient 1, an 81-year-old woman with two years of cognitive decline and prior lobar hemorrhages, developed focal status epilepticus. MRI revealed new white matter changes and leptomeningeal enhancement. She improved after intravenous methylprednisolone and remained stable without maintenance immunosuppression.

Patient 2, an 81-year-old woman with a slowly progressive cognitive decline, was admitted for an acute confusional episode. MRI revealed diffuse vasogenic edema, scattered microhemorrhages, and minimal leptomeningeal enhancement. She was treated with intravenous methylprednisolone followed by a short oral steroid taper, resulting in clinical improvement. However, she developed recurrent symptoms requiring a longer steroid taper over a year, ultimately achieving clinical and radiological stability.

Patient 3, a 72-year-old woman with a fulminant course with recurrent subarachnoid hemorrhage, seizures, and encephalopathy. MRI revealed leptomeningeal enhancement and infarcts; biopsy confirmed CAA-rI. She deteriorated despite intravenous methylprednisolone, requiring cyclophosphamide, which was complicated by pancytopenia. After three cycles and a prolonged steroid taper, she showed modest functional improvement but remained severely disabled.