Cerebral amyloid angiopathy with inflammation (CAA-I) is a less well-recognized clinically and radiologically distinct subtype of CAA. We aim to describe the imaging manifestations of this uncommon entity.

A retrospective review of the medical records and imaging database yielded 9 patients with clinical and radiological findings compatible with CAA-I. The neurological findings at presentation, MRI findings including the presence of white matter involvement, mass effect, microhemorrhages and contrast enhancement, treatment provided and outcome were evaluated. Brain biopsy specimens, when available were also reviewed.

All patients presented with subacute cognitive decline. In all 9 patients, confluent white matter lesions with mass effect were observed. Eight out of 9 patients demonstrated foci of microhemorrhage, while in 1, the microhemorrhages appeared 12 weeks after the initial examination. No significant parenchymal or meningeal enhancement was present in any patient. In 4 patients, brain biopsy was consistent with CAA-I. Immunosuppressive therapy was initiated in all patients, leading to full recovery in 5.

CAA-I is characterized by the subacute onset of dementia, a distinct pattern of confluent white matter signal abnormality with mass effect and response to immunosuppressive therapy. Prompt recognition may help obviate brain biopsy and initiation of treatment.