Classification as an eosinophilic form of papillary renal cell carcinoma (Figure 4C–D) can be additionally supported by the presence of foamy macrophages, or by immunohistochemical staining results, such as positive vimentin (Figure 4E), very diffuse and strong labeling for alpha-methyl-acyl-coA racemase (AMACR, Figure 4F), and negative staining for KIT. The gene discussed is VIM; the disease is papillary renal cell carcinoma.