Primary Extremity Liposarcoma: MRI Features, Histopathology, and Clinical Outcomes.

Objective This study aimed to describe magnetic resonance imaging (MRI) features of extremity liposarcoma (LPS) subtypes, correlating with histopathology and clinical outcomes. Methods In this retrospective study, we included 125 patients (80 men, 45 women; mean age, 53 years) with extremity LPS [23 atypical lipomatous tumor (ALT), 9 dedifferentiated (DDLPS), 70 myxoid (MLPS), 23 pleomorphic (PLPS)]. Pretreatment MRI of primary tumors in 56 patients (10 ALT, 4 DDLPS, 28 MLPS, 14 PLPS) was reviewed. Results All subtypes were predominantly T1 isointense relative to skeletal muscle (DDLPS = 3/4, MLPS = 28/28, PLPS = 13/14) and T2 hyperintense (ALT = 10/10, DDLPS = 3/4, MLPS = 28/28, PLPS = 14/14) except for ALT which were T1 hyperintense (8/10). Within MLPS, high grade was associated with unencapsulated margins (P = 0.05) and solid, nodular enhancement (P < 0.0001). Peritumoral edema (P = 0.03) and T2 heterogeneity (P = 0.05) predicted pulmonary (rather than extrapulmonary) metastases in MLPS. Tumor subtype correlated with mortality (P = 0.04). Conclusions The MRI features can help to distinguish between extremity LPS subtypes, and can predict histopathologic grade and metastatic pattern in myxoid LPS.