Biphasic sarcomatoid carcinoma (carcinosarcoma) of the renal pelvis with heterologous chondrogenic differentiation.

A case of a man with biphasic sarcomatoid carcinoma of the right kidney with chondrosarcomatous foci and with invasion of the pelvic mucosa and submucosa into the peripelvic adipose tissue is presented. In situ carcinoma of the urothelium of the right renal pelvis and proximal ureter was also noted. Comments on the nomenclature of malignant tumours with apparently mixed carcinomatous and sarcomatous phenotypes and a hypothesis on the histogenesis of these tumours are presented. Cytokeratin and p53 protein expression patterns, and the results of angiogenesis quantification are consistent with an epithelial-to-mesenchymal conversion induced by the stroma.