Pathological and immunohistochemical findings of an autopsy case of adult moyamoya disease.

Moyamoya disease is vaso-occlusive disease involving the arteries of the circle of Willis that is accompanied by a compensatory recruitment of a vascular network. The pathological and immunohistochemical findings of an autopsy case of hemorrhagic moyamoya disease in a 69-year-old woman are described in the present report. The autopsy findings of the brain revealed cerebral and intraventricular hemorrhage with edema. The left anterior cerebral artery, bilateral middle cerebral arteries and left posterior cerebral artery were marked narrowing, and the other arteries revealed mild narrowing. Microscopically, the arteries of the circle of Willis showed narrowed lumen, fibrocellular intimal thickening, marked tortuousness of internal elastic lamina and attenuation of media. The thickened intima was composed of smooth muscle cells. The vessels with dilated or irregular-shaped lumen suggested abnormal vascular networks demonstrated by angiography. In this case, no correlation between the abnormal vascular network and expression of VEGF or VEGF receptor was disclosed. It was hypothesized that abnormal vascular networks might be composed of collateral vessels in relation to various pathological changes of the arteries, such as occlusion and stenosis, and intracranial hemorrhage in patients with moyamoya disease might occur as a result of rupture of arteries including abnormal vascular networks.