[A Case of Fibroepithelial Polyp that was Difficult to Distinguish from Renal Pelvic Carcinoma].

A 56-year-old woman presented with left flank pain. Computed tomography revealed hydronephrosis and a 35 mm mass in the left renal pelvis. Ureteroscopy revealed a white elevated lesion in the left renal pelvis. Tissue biopsy was performed and the histological findings showed no evidence of malignancy. Urine cytology was class III. Based on these results, we could not completely rule out malignancy. Left retroperitoneoscopic nephroureterectomy was performed and a pedunculated white mass was found in the renal pelvis. The pathological diagnosis was a fibroepithelial polyp of the renal pelvis. Fibroepithelial polyps in the urinary tract are relatively rare, and those in the renal pelvis even more so. When the preoperative diagnosis shows no malignant findings, fibroepithelial polyps should be considered as a differential diagnosis.