CT appearance of hemangiopericytoma.

Hemangiopericytoma is an uncommon tumor that may occur anywhere in the body but is most often found in the retroperitoneum, extremities, and nasopharynx. The CT evaluation of five malignant hemangiopericytomas (two retroperitoneal, two nasopharyngeal, one thigh) revealed speckled calcifications in all cases. The lesions in the retroperitoneum and thigh were large and lobular, with areas of cystic-degeneration or hemorrhage. Computed tomography of a rare, benign osseous hemangiopericytoma demonstrated characteristics of a slow-growing bone tumor with a cortical break in the proximal femur. The homogeneously enhancing, noncalcified mass found in the posterior fossa appeared similar to the typical benign hemangiopericytoma reported in this location by other authors.