Sarcomatoid carcinoma of the urinary bladder: A clinicopathologic and immunohistochemical analysis of 14 patients

Sarcomatoid carcinoma of the urinary bladder is a rare entity, in which bot h the histogenesis and biological behavior remain controversial. We herein describe the clinicopathologic and immunohistochemical profiles of sarcomat oid carcinomas and discuss the significance of cell adhesion molecules in t he development of this peculiar neoplasm. The authors examined formalin-fix ed and paraffin-embedded tissue samples from 14 patients with sarcomatoid c arcinoma of the urinary bladder, An immunohistochemical analysis was perfor med by using antibodies against epithelial and mesenchymal antigens as well as adhesion molecules. Most patients suffered from an advanced stage of th e tumor, extending to the muscular layer (7 cases) or to the perivesical ti ssues (5 cases). Microscopically, all 14 tumors were composed predominantly of a carcomatoid component and an obviously carcinomatous component. The s arcomatoid component was composed of a mixture of spindle cells, round cell s, and pleomorphic giant cells. The carcinomatous components consisted of p apillary or nonpapillary high-grade transitional cell carcinoma (TCC), The zones of gradual transition between the carcinomatous and the sarcomatous e lements were focally apparent in each tumor. The findings of an immunohisto chemical examination indicated that both carcinomatous and sarcomatoid comp onents expressed epithelial antigens (pankeratin or EMA), even though the s taining pattern varied from case to case. As for cell adhesion molecules, t he carcinomatous components were positive For E-cadherin (8 of 12), CD44s ( 8 of 12), and CD44v6 (6 of 12). Although the sarcomatoid components were al so positive For E-cadherin (5 of 12), CD44s (4 of 12), and CD44v6 (3 of 12) , these rates were lower than those in the carcinomatous components. Six pa tients: died of their disease between 5 and 36 months after the diagnosis, was made. The recognition of sarcomatoid carcinomas has important therapeut ic and prognostic implications. It seems appropriate to treat these neoplas ms in the same manner as conventional high-grade TCCs with similar degrees of invasion. We consider that sarcomatoid carcinomas should be regarded as a high-grade carcinoma that shows a prominent pseudosarcomatous dedifferent iation. The sarcomatoid component of sarcomatoid carcinomas may result from either anaplastic changes or dedifferentiation related to die process of l osing cell adhesion molecules. Copyright (C) 2000 by W.B. Saunders Company.