Urothelial leiomyomatous hamartoma of the kidney.

A 34-year-old woman presented with a renal pelvic mass. A nephroureterectomy including a cuff of bladder, was performed and pathologic examination revealed a hamartoma involving the renal parenchyma and pelvis. The pelvic portion of the tumor was composed of papillae lined by urothelium; the parenchymal portion of the tumor was composed of tubules within a fibromuscular stroma. The authors propose that this is a distinct entity not previously described in the literature.