Carcinosarcoma of the Urinary Bladder—An Aggressive Tumor With Diverse Histogenesis

Objective.—Carcinosarcomas of urinary bladder are rare malignant neoplasms. Seventy-eight cases have been previously described. The histologic composition of these tumors is variable, but diagnosis requires the presence of both epithelial and mesenchymal malignant components. We report 4 additional cases, with an emphasis on unusual histologic features. Methods.—Histologic and immunohistochemical examinations were performed on bladder tumors from 4 patients. Clinicopathologic features of previously reported and current cases were reviewed and summarized. Results.—Four patients (3 men, 1 woman) age 54 to 77 years were found to have polypoid masses in the urinary bladder. In all cases, histologic examination showed biphasic neoplasms with distinct mesenchymal and epithelial components. The morphologic and immunohistochemical characteristics of the tumors varied. One of the cases was remarkable for the presence of liposarcoma, malignant peripheral nerve sheath tumor, and micropapillary urothelial carcinoma. Two of the patients died 2 years after diagnosis, which is consistent with the previously reported aggressive nature of urinary bladder carcinosarcomas. Conclusions.—Carcinosarcomas of the urinary bladder are rare, aggressive malignant neoplasms. To our knowledge, a liposarcomatous component has been reported in only 1 case previously, and components of micropapillary urothelial carcinoma and malignant peripheral nerve sheath tumor have not been reported previously in carcinosarcomas of the urinary bladder. Because of the aggressive biologic behavior of these tumors, they should be identified promptly and treated appropriately.