One Hundred Cerebral Microhemorrhages: Rethinking Cerebral Amyloid Angiopathy in the Era of Amyloid-Targeted Antibodies.

We report a case of probable cerebral amyloid angiopathy (CAA) presenting with almost 100 cerebral microhemorrhages in an apolipoprotein E 4 (APOE4) homozygous subject with mild cognitive impairment (MCI). CAA is highly prevalent in autopsy studies and may impact over 100 million individuals worldwide; however, it remains substantially underdiagnosed clinically. CAA raises the risk for intracerebral hemorrhages as well as amyloid-related imaging abnormalities (ARIA) with amyloid-targeted antibodies. CAA is especially a quandary in APOE4 homozygotes who are at greatest risk for both Alzheimer's disease (AD) and ARIA. This case highlights the urgent need for greater diagnostic awareness and therapeutic development.