Hemangiopericytoma: A clinicopathologic and ultrastructure study

Hemangiopericytoma is a rare mesenchymal tumor arising from special cells known as “pericytes,” present on the outer walls of the capillaries. This neoplasm, first described by Stout in 1942, can occur in any part of the body but the majority are confined to the trunk and lower limbs. It can affect both sexes equally and all age groups, but occurs principally in adults in the 4th decade of life. Occasionally, the spectrum of variations in its histologic features lead to misinterpretation; such errors can be avoided by the use of electron microscopy. Approximately 50% are malignant and certain criteria are used to differentiate the benign from its malignant counterpart. This paper is based on a study of 6 patients seen in a special referral center during a 10‐year period; in 2 patients electron microscopic studies were undertaken to confirm the diagnosis. Four patients (66%) died within 5 years, and the remaining 2 are alive without recurrence at 6 years and 32 months, respectively. The literature on hemangiopericytoma is briefly reviewed from a surgeon's viewpoint, with special reference to the place of preoperative tumor embolization and recent advances made in the field of adjuvant radiotherapy and chemotherapy.