Considering the existence of a transitional zone (6/7) between the two components of this tumour, they might coexpress vimentin, CAIX, PAX8, PAX2, and HIF1α; however, they had their own characteristics, suggesting that these components are two morphological manifestations of the same tumour and not a simple collision between renal cell carcinoma and haemangioblastoma. This evidence concerns the gene HIF1A and renal cell carcinoma.