Proffered Papers— Diagnostic Imaging/Pathology

ROUND-CELL AND MYXOID LIPOSARCOMA OF THE EXTREMITIES. A CLINICOPATHOLOGIC STUDY OF 102 CASES

Pellacani A, Pignatti G, Bertoni F, Giunti A, Baldini N (Istituti Ortopedici Rizzoli, 40136 Bologna, Italy)

We evaluated the clinical and pathologic features of 102 patients with biopsy proven myxoid or round cell liposarcoma examined at a single institution between 1977 and 1999. Routine hematoxylin and eosin stained slides of all cases were reviewed. Morphologic variables evaluated included percent of round cell differentiation, percent of lipoblast differentiation, and presence of tumor necrosis. Clinical follow-up was available for all patients. Flow cytometry for determination of DNA ploidy was performed on fresh tissue available from 28 cases. Survival were performed by the Kaplan-Meier test using the approximate chi-square statistic for the log-rank test.

Age at diagnosis ranged from 12 to 78 years (median: 46 years), with a significant difference between males (median: 35 years) and females (median: 66 years). The single most common location was the thigh (70 cases). Histologically, round cell differentiation was present in 35 cases. Spontaneous tumor necrosis was noted in 11 cases. By flow cytometry, 27 tumors were diploid, and 1 was aneuploid. Twenty-four patients developed metastases at a mean of 22 months after diagnosis.

With statistical analysis, age (>45 years), male sex (p <0.05), percent of round cell differentiation (>25%) (p<0.05), and the presence of spontaneous tumor necrosis were associated with a poor prognosis. No correlation was observed between DNA ploidy and percent of round cell differentiation or clinical outcome.