Sarcomatoid Carcinoma of Renal Pelvis Involving Ureter and Renal Parenchyma with Heterologous Osteosarcomatous Differentiation: A Case Report and Review of Literature.

Sarcomatoid carcinoma is a highgrade rare malignant tumor with both epithelial and mesenchymal components. Sarcomatoid carcinoma in the upper urinary tract is very rare. We reported here a case of sarcomatoid carcinoma of renal pelvis with osteosarcomatous differentiation, with involvement of the ureter and renal parenchyma in a 68-year-old female. Histologically, predominant pleomorphic spindle cell sarcoma component with osteoid production and urothelial carcinoma component with in situ areas were identified. Immunohistochemical analysis showed vimentin positivity in sarcomatous component and cytokeratin positivity in carcinomatous component.