Renal pelvis sarcomatoid carcinoma with renal vein tumor thrombus: A case report and literature review.

Background: Renal pelvis sarcomatoid carcinoma (RPSC) is a rare and aggressive malignancy whose diagnosis is difficult because radiological imaging results can lead to misclassification as a more common type of renal tumor. In addition, clinical management of patients with RPSC is difficult because of the limited efficacy of available treatments. In this study, we present a comprehensive description of a patient who presented with RPSC and a simultaneous renal vein tumor thrombus.