Fibroepithelial polyps of the renal pelvis: report of two cases and review of the literature.

Benign tumors of the urinary tract are rarer than transitional cell carcinomas. Among the benign tumors we have those of epithelial origin (papillomas or low grade transitional cell carcinomas) and those of mesodermal origin (fibrous and angiomatous polyps, hemangiomas and lymphangiomas and neurofibromas), together with a group of miscellaneous lesions including endometriosis, amyloidosis and granulomas. The fibroepithelial polyps of the urinary tract represent between 2-6% of all the benign tumors. This rare tumor is located more frequently in the ureter and only in 11 cases reported since 1929 the location was the renal pelvis. Between 1976 and 1994 we have seen three cases of fibroepithelial polyps of the urinary tract, two of them affecting the renal pelvis and one of them affecting the ureter. We report the cases located in the pelvis and make a review of the cases reported in this location in the last years and discuss the clinical, radiological and cytological criteria that can lead to a preoperative diagnosis of this entity avoiding an unnecessary nephroureterectomy.