Giant mixed-type perinephric liposarcoma.

Retroperitoneal fatty tumours are uncommon occurrences in current urologic practice, the differentials being lipomas, liposarcomas and extra-renal angiomyolipomas (AML). We report an unusual case of a 48-year-old Chinese female who presented with a 6.2 kg giant mixed-type liposarcoma in the left perinephric space, invading into the renal cortex and parenchyma. Extirpative surgery with left radical nephrectomy was performed, and histology confirmed liposarcoma with both myxoid and well-differentiated elements. The patient remains well and disease-free at 6-month follow-up. We review the literature on the diagnosis and management of these perinephric lipomatous lesions. We also discuss the diagnostic dilemma in differentiating such malignancies from benign angiomyolipomas in the perinephric area on conventional radiological imaging, and its direct implications with respect to extent of surgery and renal preservation.