[A case of hemangiopericytoma in the pelvic retroperitoneum]

A case of hemangiopericytoma in the pelvic retroperitoneal space is described. A 54-year-old-male had a retroperitoneal mass which had been incidentally detected during evaluation of microscopic hematuria. The pelvic arteriogram revealed an extremely hypervascular mass at the arterial phase and intensive, longlasting and well-demarcated tumor stain at the capillary phase, which were characteristic of hemangiopericytomas. Resection of the tumor was difficult due to a well developed vessel mesh around the tumor and adhesion to the surrounding tissues. The tumor weighted 45 g. The patient has remained free of disease for 29 months postoperatively. Since histopathological malignant features of hemangiopericytoma are still obscure, long term and close follow up is important.