Unusual renal pelvic tumor containing transitional cell carcinoma, adenocarcinoma and sarcomatoid elements (so-called sarcomatoid carcinoma of the renal pelvis). A case report and review of the literature.

A case of sarcomatoid carcinoma of the renal pelvis in a 66-year-old male is reported. The patient underwent left nephroureterectomy because of renal pelvic tumor and hydronephrosis. Left renal calcification and atrophy had been diagnosed in the patient about thirty years previously. The tumor showed a polypoid configuration and occupied the renal calyces. Histologically, not only solid nests of transitional cell carcinoma (TCC) and adenocarcinomatous glands but also large spindle-shaped cells with bizarre nuclei simulating sarcoma were identified. Immunoreactive keratin and epithelial-membranous antigen (EMA) were demonstrated in the sarcomatoid cells, indicating that they were of epithelial origin. So far, only 10 cases of so-called sarcomatoid carcinoma or carcinosarcoma of the renal pelvis have been reported in the world. In this report, we summarize the pathological findings of previously reported cases and discuss the histogenesis of this rare tumor.