Transitional cell carcinoma of the renal pelvis with choriocarcinomatous differentiation. Immunohistochemical and immunoelectron microscopic assessment of human chorionic gonadotropin production by transitional cell carcinoma of the urinary bladder.

ABSTRACT

BACKGROUND: There have been 12 documented cases of choriocarcinoma arising in the urinary bladder, either alone or in combination with other epithelial tumors. It has been shown that some high-grade transitional cell carcinomas (TCC), without obvious syncytiotrophoblastic elements, can produce human chorionic gonadotrophins (HCG). METHODS: A case of choriocarcinoma, in association with high-grade TCC of the renal pelvis, was encountered in an 80-year-old man. For additional evaluation of HCG production by TCC, 25 consecutive cases of invasive high-grade TCC of the bladder were stained with an anti-HCG antibody. Immunogold staining also was performed in two of the cases studied. RESULTS: Immunoperoxidase staining of the renal pelvis tumor showed focal positivity for HCG within the TCC and a more intense reaction as the tumor cells differentiated into choriocarcinoma elements. Seven of the 25 cases (28%) displayed varying degrees of reactivity within individual cells or groups of cells. In an additional case, typical syncytiotrophoblastic giant cells without cytotrophoblasts were seen in a high-grade TCC. Immunogold studies demonstrated positive labeling in the cytoplasm of carcinoma cells in a case of TCC without syncytiotrophoblasts and in the syncytiotrophoblastic giant cells in the one case in which these were present. CONCLUSIONS: The findings support a metaplastic origin of cases of choriocarcinoma arising primarily in the urothelial tract.