Acute hemorrhage in late radiation necrosis of the temporal lobe: report of five cases and review of the literature.

Hemorrhage in late cerebral radiation necrosis is a rare complication after radiotherapy for intracranial and extracranial neoplasms. We report 5 cases of acute hemorrhage in late radiation necrosis of the temporal lobe following radiation therapy for nasopharyngeal carcinoma. In a review of the literature, the authors identified a total of 27 such cases. The interval period between the onset of hemorrhage and cranial irradiation is long (mean = 7.8 years). The most prominent histological feature was the proliferation of large, dilated and thin-walled new blood vessels in a background of gliosis and fibrinoid necrosis of vessels. Rupture of these thin-walled new blood vessels is the proposed mechanism of hemorrhage in this condition.