Leiomyosarcoma arising from the blind end of a bifid renal pelvis.

Sarcoma of the kidney is a rare condition. Leiomyosarcoma is the most common of the kidney sarcomas. Renal leiomyosarcoma usually originates from the smooth muscle layers of the kidney, for example, the renal capsule and renal vessels. Renal pelvis neoplasms, however, are primarily transitional cell carcinomas, and renal pelvis leiomyosarcomas are extremely uncommon. Renal pelvis leiomyosarcoma has never been reported in Korea. Moreover, no more than 10 cases have been reported internationally. However, none of these were associated with kidney abnormalities. Here we describe a case of leiomyosarcoma that originated from the blind end of a bifid renal pelvis.