Moyamoya syndrome after cranial irradiation for bone marrow transplantation in a patient with acute leukemia.

It is well known that radiation-induced vasculopathy and arteritis are two of the complications of whole brain radiation therapy. Moyamoya syndromes after cranial irradiation among patients with brain tumors were previously reported. However, we could find only three cases of prophylactic cranial irradiation for hematological disorders and no case of cranial irradiation before bone marrow transplantation in patients with acute leukemia. We recently treated a boy who developed moyamoya vessels 1.5 years after cranial irradiation for bone marrow transplantation for acute leukemia. This is the first report of moyamoya syndrome after cranial irradiation for bone marrow transplantation. The mechanism and incidence of vasculopathy after cranial irradiation are unclear. It would be useful to accumulate data and reveal the etiology of moyamoya vessels formation after cranial irradiation.