Changing venous pattern in a hemangioblastoma resembling an arteriovenous malformation

A patient with cerebellar hemangioblastoma underwent two successive cerebral arteriograms within a 48-hour period. The first arteriogram suggested an arteriovenous malformation. The second angiogram showed a dramatic change with nearly total absence of the earlier dilated draining veins. This change was found on examination of the surgical specimen to be caused by venous thrombosis.