Chromophobe Renal Cell Carcinoma with Sarcomatoid Differentiation (osteosarcomatous and chondrosarcomatous differentiation)-A Case Report and Comprehensive Review.

Chromophobe renal cell carcinomas (ChRCCs) have a good prognosis and comprise approximately 5-7% of renal cell carcinomas (RCCs). The sarcomatoid differentiation in RCC is found in around 5-10% of cases; however, in ChRCC, it is much less than in other RCCs and poorly responds to chemotherapeutic agents. A study by de Peralta-Venturina et al. found 9% sarcomatoid differentiation in chromophobe RCC. We present the case of a 58-year-old female with a left abdominal mass diagnosed as ChRCC with the existence of sarcomatous differentiation including osteosarcomatous and chondrosarcomatous, which are of adverse prognosis. Osteosarcoma-like divergent differentiation in RCC is extremely rare, with limited documented cases. It should be carefully considered in evaluating and managing renal masses due to its potential impact on clinical outcomes.