Aggressive co-existence: Collecting duct and clear cell carcinoma in the same kidney.

As in every organ, synchronous multiple cancers are rarely encountered in kidneys. In the literature, mostly co-existence of renal cell carcinoma and transitional cell carcinoma was reported. In the literature, the co-existence of collecting duct carcinoma and clear cell carcinoma was described only for a few cases with different patterns. With these two cases, we aimed to present a very rare entity with synchronous existence of clear cell renal cell carcinoma and collecting duct carcinoma in the same kidneys.