Liposarcoma is the most common soft tissue malignancy and usually occurs in the retroperitoneum or the extremities but rarely in the kidney. In this article, we report a case of a 71-year-old female patient who presented with abdominal lump and left flank pain for 1 month. An abdominal contrast-enhanced computed tomography scan demonstrated a 12 cm × 7 cm solid mass arising from the upper pole of left kidney and another 8 cm × 6 cm low-density retroperitoneal mass with fat density. Radical nephrectomy of the left kidney and resection of the retroperitoneal mass were performed. Surprisingly, pathological examination revealed a high-grade sarcoma (with minor lipomatous component) in the left kidney and a retroperitoneal well-differentiated liposarcoma. MDM2 gene amplification was identified by fluorescence in situ hybridization in both tumors, supporting final diagnosis of dedifferentiated liposarcoma of the kidney and well-differentiated liposarcoma of the retroperitoneum.
Keywords: MDM2; liposarcoma; renal tumor; retroperitoneal tumor.