57

Chromophobe renal cell carcinoma (ChRCC) is the third most common histological subtype of renal tumors, mainly affecting patients between the ages of fifty and sixty. It is unique in many aspects, with sporadic and constitutional forms, and a predominantly indolent course with a five-year survival rate of around 90 percent and rare metastases. At gross examination, the tumors are solid, well-demarcated, and beige-colored, with a variety of microscopic architectural features, including a mixture of clear and eosinophilic cells with specific nuclear traits. These tumors usually exhibit CK7+/CD117+ expression on immunohistochemistry, and their cytogenetic profile shows multiple recurrent chromosomal losses. Similarly, non-specific TP53, PTEN, and CDKN2A mutations are sometimes found. These aspects, together with a difference in oxidative phosphorylation, reflect an anomaly in the quantity and quality of mitochondria within the cytoplasm of tumor cells. It is therefore important to differentiate ChRCC from other renal tumors, notably renal oncocytomas (benign tumors) and eosinophilic renal cell tumors. In terms of prognosis, large size, advanced stage, the presence of a sarcomatoid component, and tumor necrosis are all markers to look out for. These markers are important as treatment for these tumors is essentially surgical; only a few of the general treatments used for other histological types of renal cell carcinoma have proven to be effective for advanced-stage ChRCC.