Retroperitoneal lipogranuloma mimicking recurrence of renal cell carcinoma after laparoscopic partial nephrectomy

Lipogranuloma is a rare inflammatory reactive process often reported to occur in the dermis and subcutis in the cosmetic surgery field.1 It very rarely occurs in the retroperitoneum. We present a case of retroperitoneal lipogranuloma mimicking metastases of renal cell carcinoma (RCC) after laparoscopic partial nephrectomy. A 63-year-old man who underwent laparoscopic left partial nephrectomy for RCC one year earlier had developed a left retroperitoneal tumor during postoperative surveillance. The tumor looked identical to an implant or recurrence of RCC on contrast-enhanced computed tomography (CT) and 18F-fluorodeoxyglucose positron emission tomography/CT. We resected the tumor, and pathology showed a lipogranuloma.