The coexistence of multiple and synchronous primary neoplasms in the same organ (including kidney) has only rarely been described in the literature. We herein present a case of collecting duct carcinoma (CDC) combined with papillary renal carcinoma (RCC) having a 57-month disease-free survival. CDC is a rather rare and aggressive neoplasm of the kidney. Sharing probably the same embryological origin, synchronous or metachronous association with in situ or papillary transitional cell carcinoma (TCC) may be found; association with RCC has been only once reported in the literature. The high incidence of c-erbB-2 oncogene amplification in CDC further characterizes this tumor as a separate entity from renal cell carcinoma, and shows some genetic characteristics in common with TCC. The histohgical diagnosis of Bellini CDC can be confirmed by the positive immuno-histochemical staining with a collecting duct marker and distal tubule marker and negative staining with a proximal tubule marker
