Figure 3d: Small solid mass in interpolar region of left kidney in a 57-year-old man with a history of prostate cancer. (a) Transverse CT image shows enhancing 3.5-cm left renal mass (arrowhead). (b) CT-guided percutaneous biopsy, shown on transverse CT image, was performed with patient in the prone position by using a 25-gauge needle (arrow). Cytologic preparations stained with Wright-Giemsa stain (not shown) revealed oncocytic cells. At further staining with (c) epithelial membrane antigen, as demonstrated by brown color, and (d) Hale colloidal iron stain, as demonstrated by blue color, the cells obtained at biopsy were positive. Diagnosis was chromophobe renal cell carcinoma. (Original magnification for c and d,x400.)