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 wit h chondrosarcomatous foci and with invasion of the pelvic mucosa and submuc osa into the peripelvic adipose tissue is presented. In situ carcinoma of t he urothelium of the right renal pelvis and proximal ureter was also noted. Comments on the nomenclature of malignant tumours with apparently mixed ca rcinomatous and sarcomatous phenotypes and a hypothesis on the histogenesis of these tumours are presented. Cytokeratin and p53 protein expression pat terns, and the results of angiogenesis quantification are consistent with a n epithelial-to-mesenchymal conversion induced by the stroma.