Urothelial carcinoma of the renal pelvis with choriocarcinomatous features: genetic evidence of clonal evolution.

Urothelial carcinoma with choriocarcinomatous features is a rare malignancy arising in the urinary bladder or renal pelvis. We report the case of a 60-year-old man with a biphasic neoplasm of the right kidney composed of papillary urothelial carcinoma and choriocarcinoma. Widespread hepatic and pulmonary metastases with choriocarcinomatous features were found on autopsy 6 weeks after initial diagnosis. Chromosomal analysis revealed a close genetic relationship between the papillary urothelial and choriocarcinomatous tumor components, documenting for the first time that choriocarcinoma of the renal pelvis results from clonal evolution of urothelial carcinoma with acquisition of trophoblastic differentiation.