The varied radiographic manifestations of retroperitoneal malignant fibrous histiocytoma revealed through 27 cases.

Malignant fibrous histiocytoma, a pleomorphic sarcoma, represents the most common soft tissue sarcoma of late adult life. Approximately 15 per cent of the cases of malignant fibrous histiocytoma arise within the abdominal cavity or retroperitoneum. Although tumors in this series arose in many different sites, their proximity to the kidney necessitated a nephrectomy in 44 per cent of the cases (12 of 27). In 3 cases calcification was noted, which varied from a few small speckled areas to extensive large, coarse densities. The masses tended to compress or displace adjacent structures and vessels radiographically. Renal, duodenal and cecal invasion occasionally occurred. Ultrasonically, most tumors were hypoechoic (9 cases), with a few having a mixed pattern (2). On computerized tomography the masses were well circumscribed, with computerized tomography numbers in the range of solid tissue except for a few small areas of decreased density. The vascularity was variable, with 8 tumors being hypovascular and 8 showing a moderate to hypervascular pattern. Interestingly, the tumor derived a part of its blood supply from the renal vasculature in 12 cases (44 per cent). Even though malignant fibrous histiocytoma often was diagnosed incorrectly as an intrarenal or adrenal neoplasm, a cleavage plane usually could be identified between the tumor and the renal parenchyma in 1 of the studies, especially on the angiogram. This finding suggested its extrarenal origin. Knowing the tendency of malignant fibrous histiocytoma to arise from or be physically near the kidney and/or adrenal gland in elderly men may be of some diagnostic value.