Renal Parenchymal Defects Occasionally Observed in Non–Well-Differentiated Perirenal Liposarcomas Unlike in Well-Differentiated Types

Objective: This study aims to clarify the frequency of renal parenchymal defects and deformations in each subtype of perirenal liposarcomas and to compare the differences between well-differentiated and non–well-differentiated types. Methods: Patients with perirenal liposarcomas seen between July 2004 and June 2024 were included. Two radiologists blinded to the subtypes retrospectively evaluated CT or MR images for renal parenchymal defects and deformations. Frequencies of these findings were compared between well-differentiated versus non–well-differentiated types using the Fisher test. Results: Forty-two patients (mean age: 66.3±11.5 y; 15 men) with perirenal liposarcomas were included. Renal parenchymal defects and deformations were observed in 0 (0%) and 1 (7.7%) of 13 well-differentiated, 5 (29.4%) and 6 (35.3%) of 17 dedifferentiated, 3 (37.5%) and 0 (0%) of 8 myxoid, and 1 (25.0%) and 1 (25.0%) of 4 pleomorphic types, respectively. Non–well-differentiated liposarcomas had higher frequencies of renal parenchymal defects and deformations compared with well-differentiated liposarcomas [9 of 29 (31.0%) vs. 0 of 13 (0%), P=0.038 and 7 of 29 (24.1%) vs. 1 of 13 (7.7%), P=0.398]. Conclusion: Renal parenchymal defects can be occasionally observed (31.0%) in non–well-differentiated perirenal liposarcomas unlike well-differentiated liposarcomas.