Synchronous collecting duct carcinoma and papillary renal cell carcinoma: a case report and review of the literature.

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 orpapillary 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 histological diagnosis of Bellini CDC can be confirmed by the positive immunohistochemical staining with a collecting duct marker and distal tubule marker and negative staining with a proximal tubule marker.