Abstract
The simultaneous occurrence of renal cell carcinoma (RCC) and urothelial carcinoma (UC) in the same kidney is extraordinarily rare, and is also known as multiple primary malignant tumors. The present study reports the case of a 76-year-old female with synchronous ipsilateral RCC and UC of the renal pelvis, who underwent operation, chemotherapy and reoperation when recurrence of RCC or UC was identified. Cluster of differentiation 44 (CD44) is one of the promising markers for identifying cancer stem cells in various solid tumors, along with aldehyde dehydrogenase 1 A1 (ALDH1A1). Detection of CD44 and ALDH1A1 prior to and subsequent to chemotherapy could provide useful prognostic information. New treatments against the cancer stem cells fraction should be used in combination with chemotherapy to improve the outcome for patients with overexpression of CSC markers.