A case of tubulocystic carcinoma simultaneously occurring with clear cell type renal cell carcinoma and micropapillary urothelial carcinoma of bladder.

The coexistence of multiple and synchronous primary neoplasms in the genitourinary system has rarely been described in the literature. To our knowledge, this is the first report of a very rare tumor, a "tubulocystic carcinoma," simultaneously occurring with micropapillary urothelial carcinoma in the bladder and clear cell type renal cell carcinoma in the same kidney. Tubulocystic carcinoma is a recently entitled tumor. It had been thought to arise from the distal collecting duct for a period of time and was therefore named as a low-grade collecting duct carcinoma. Microscopically, the tumor is defined as being tubulocystic or having tubulopapillary architecture and a low nuclear grade with hobnail morphology. Its progression and treatment protocol are uncertain.