Additional immunohistological markers such as RCC, CD10, carboanhydrase IX, PAX8, and p63 are useful to differentiate CCCRC from other clear cell tumors, e.g., renal cell carcinomas, malignant Müllerian tumors, and squamous cell carcinomas of the anal canal, which all may affect the colorectal tract [2]. This evidence concerns the gene PAX8 and squamous cell carcinoma.