RESUMEN
Sarcomatoid carcinomas are malignant epithelial neoplasms in which the tumor cells assume a partial or complete spindle cell pattern of growth, leading to the erroneous classification of some true carcinomas as sarcomas. These spindle cells are malignant and manifest various amount of both vimentin and cytokeratin. Positive reaction of some of the spindle cells for cytokeratin antibodies is confirmatory. Clinical features do not differ significantly from those of patients with high-grade transitional cell carcinoma. So far, 13 cases of sarcomatoid transitional cell carcinoma of the renal pelvis have been reported in English and Korean literature. In this report, we describe clinicopathologic features of recently observed two cases of sarcomatoid transitional cell carcinoma of the renal pelvis and summarize the pathologic findings of previously reported cases with review of the literature.