Hybrid Bladder Tumor: Urothelial Carcinoma With Squamous Cell Differentiation, Urothelial Sarcomatoid Carcinoma, and Concurrent Primary Mucinous Adenocarcinoma With Metastasis to the Penis

The most common histological variants of bladder cancer include urothelial, squamous, and adenocarcinoma. In high-grade, invasive urothelial carcinoma, divergent differentiation can be observed, including glandular, squamous, trophoblastic, and small-cell types. Urothelial sarcomatoid carcinoma is characteristic of advanced carcinomas and is considered a possible common end route for all epithelial carcinomas. Adenocarcinoma of the bladder refers exclusively to true glandular carcinomas. Hybrid tumors are extremely rare and consist of more than one tumor type within the total tumor mass. Penile metastases are extremely uncommon, and there are no reported cases of metastatic adenocarcinoma of the bladder in the literature.