Histological analysis of microbleed after surgical resection in a patient with moyamoya disease.

A 65-year-old male with moyamoya disease underwent surgical resection of a microbleed simultaneously with revascularization surgery. Histological examination identified several fragile arteries surrounding the microbleed. Microbleeds detected by T2*-weighted magnetic resonance imaging are considered to be a general marker of vascular vulnerability in cerebral angiopathy with a tendency to bleeding. The microbleeds observed in patients with moyamoya disease probably originate in bleeding from the fragile arteries.