Collision of transitional cell carcinoma and renal cell carcinoma. An immunohistochemical study and review of the literature.

A case characterized by a rare synchronous occurrence of transitional cell carcinoma (TCC) of the renal pelvis and renal cell carcinoma (RCC) in the same kidney is presented. A retrospective analysis of 23 similar cases reported in the English literature over the last 71 years demonstrated a male-to-female ratio of 2:1, an average age of 64.5 years, and a left-to-right-side ratio of 3.2:1. The three most common findings at initial examination were hematuria (90%), flank pain (19%), and flank mass (14%). Moreover, 24% of patients had tumor metastases even at initial examination. Thirty-four percent of patients had bladder neoplasms, and 24% of them had a history of cigarette smoking. There is no tendency toward higher grade of malignancy or specific histologic pattern for TCC and RCC when they occur together in the same kidney. Immunohistochemical studies were used to examine TCC and RCC, with special attention paid to the site of their collision, which displayed multifocal lymphatic permeation. Both TCC and RCC were positive for epithelial membrane antigen (EMA) and cytokeratins identified by monoclonal antibodies CAM-5.2, AE1/AE3, and MAK-6. TCC was focally positive for keratin, detectable by antibody 34 beta E12, but RCC was not. The tumor tissue infiltrating the lymphatics, which seemed to be RCC, demonstrated positive staining for EMA and keratins CAM-5.2, AE1/AE3, and MAK-6 and negative staining for keratin 34 beta E12. Interestingly, the tumor in lymphatics displayed strong staining for carcinoembryonic antigen (CEA) but both TCC and RCC in the vicinity were negative. These findings suggest that keratin 34 beta E12 may play a role in the differential diagnosis between TCC and RCC and that tumor-invading lymphatics may change phenotype, including the neoexpression of CEA.