SEPTUM-LIKE STRUCTURES IN LIPOMA AND LIPOSARCOMA - MR-IMAGING AND PATHOLOGICAL CORRELATION

Objective. To-investigate the septum-like structures in predominantly lipomatous tumors, by correlating fat-suppressed MR images with histop athologic findings. Design and patients. The MR findings of three case s of well-differentiated liposarcoma (atypical lipoma), one case of li poma-like component of dedifferentiated liposarcoma. and nine cases of lipoma were analyzed. T1-, T2-, and fat-suppressed T1- weighted image s after Gd-DTPA administration were obtained. Surgical specimens from five patients (four with liposarcoma and one with lipoma) were also sc anned with a MR unit, and compared with the pathologic findings. Resul ts and conclusions. Enhancement features of lipoma and liposarcoma wer e well visualized on fat-suppressed T1-weighted images after Gd-DTPA a dministration. The septum-like structures of liposarcoma are thick and enhanced considerably, while septa of lipoma are thin and enhanced on ly slightly. Pathologically, the septum-like structures of Liposarcoma contained muscle fibers and the septa of lipoma represented fibrous c apsule, Identification of well-enhanced septa in a predominantly lipom atous tumor helps to differentiate malignant tumors horn lipomas. As t he septum-like structures of liposarcoma contain a skeletal muscle com ponent the tumor might need more extensive surgical procedures includi ng resection of adjacent muscles.