Moyamoya syndrome in an adult with essential thrombocythemia.

Moyamoya syndrome is a rare cerebrovascular disorder characterized by progressive occlusion of the supraclinoid internal carotid artery and proximal portions of the anterior and middle cerebral arteries resulting in an extensive network of collateralized blood vessels and producing a characteristic angiographic appearance. Although the pathophysiology is unclear, hematologic disorders have been associated with development of the moyamoya syndrome. A case report is presented. A 29 year-old female with a history of essential thrombocythemia developed progressive ischemic strokes. Angiography revealed characteristic moyamoya changes and pathologic examination showed intimal hyperplasia with scant collagen fibers and myxoid change. This is the first reported case of moyamoya syndrome in an adult patient with essential thrombocythemia demonstrating histological findings that suggest a shared pathophysiology with moyamoya syndrome in sickle cell anemia.