Liposarcoma of the extremities: MR and CT findings in the histologic subtypes.

The findings on images of liposarcomas of the extremities in 48 patients (26 men and 22 women aged 20-85 years) were reviewed to correlate the histologic subtypes with radiologic appearance. Computed tomographic scans were obtained in 36 patients; magnetic resonance (MR) images, in 27 patients. The study group had 19 myxoid, 12 well-differentiated, nine round cell, and eight pleomorphic liposarcomas. Well-differentiated liposarcomas were predominantly composed of fat, typically with thick septa, which were hyperintense on T2-weighted spin-echo MR images. The heterogeneity of tumor helped differentiate tumor subtypes. Eleven of 19 myxoid tumors were mildly heterogeneous. Round cell and pleomorphic subtypes, which tend to be aggressive, were generally heterogeneous. Well-differentiated liposarcomas may be confidently differentiated from other subtypes of liposarcoma. Except for the well-differentiated subtypes, liposarcomas often contain no fat. Moderate to marked heterogeneity is common in high-grade liposarcomas; myxoid liposarcomas tend to be homogeneous and may mimic cysts.