Sarcomatoid renal carcinoma is an aggressive neoplasm with clinical and radiological features similar to those of clear cell renal sarcomas. The tumor is formed by layers of malignant spindle cells that show immunohistochemical and ultrastructural characteristics of both stromal and epithelial cells, and may also contain mixoid areas of osteoclast-like giant cells, rhabdomyoblast-like pleomorphic cells as well as other rare sarcomatoid components. The authors report a case of sarcomatoid renal carcinoma in a 54-year-old male patient presenting with the classic clinical triad seen on patients with renal cell carcinomas. The typical macroscopic and microscopic features, imaging findings and differential diagnosis with true renal sarcomas are discussed.

Keywords: Renal cell carcinoma, Sarcomatoid renal carcinoma, Tumor metaplasia, Computed tomography, Ultrasonography