Liposarcoma. A clinicopathologic subtyping of 52 cases.

Fifty-two cases of liposarcoma were analyzed clinicopathologically, and were grouped into the following five types: myxoid (28 cases), well-differentiated (14 cases), pleomorphic (4 cases), round-cell (3 cases), and mixed (3 cases). Three of the 28 myxoid tumors showed a pleomorphic pattern resembling that of the myxoid variant of malignant fibrous histiocytoma, and one of the 3 round-cell tumors was considered to be a malignant counterpart of hibernoma. Ages ranged from 22 to 86 years with the average age of 49 years, the average patients with myxoid or round-cell liposarcoma being over 10 years younger than those with well-differentiated or pleomorphic liposarcoma. There was also a variation in the site of predilection of the cases: the great majority of myxoid type tumors occurred in the thigh, popliteal fossa and buttock (23 cases), while the majority of well-differentiated type tumors were seen in the retroperitoneum (10 cases). The rate of local recurrence of the tumor was 46%. Four of the 5 well-differentiated liposarcomas which recurred exhibited dedifferentiated pleomorphic components resembling those in malignant fibrous histiocytoma. The prognosis was more favorable in patients with ordinary myxoid tumors than in those with well-differentiated tumors. The overall relative five-year survival rate was 63%.