[Inverted papilloma of the renal pelvis: report of a case].

Inverted papilloma of the upper urinary tract is a rare lesion. To our knowledge, we report here the 32nd case of inverted papilloma of the renal pelvis. A 50-year-old man presented with asymptomatic gross hematria. Excretory urography showed a filling defect in the left upper calyx. Computerized tomography showed a poorly enhanced low-density area within the renal pelvis. Since radiographic findings suggested a renal pelvic tumor, the patient underwent total nephroureterectomy. Unexpectedly, a 3 x 2.5 cm polypoid tumor of the renal pelvis was consistent with inverted papilloma. Since this benign lesion is extremely rare within the upper tract and its radiographic characteristics closely resemble those of urothelial carcinoma, the preoperative diagnosis of inverted papilloma of the upper tract cannot be conclusively established even by modern imaging techniques. Therefore treatment consistent with that for urothelial carcinoma should be applied in this disease entity.