Four molecular markers including MN/CA9, vimentin, KIT, and S100A1 will be studied. These four markers have been reported to have a differential diagnostic value in renal tumors. MN/CA9 and vimentin are often found in conventional renal cancers. KIT is frequently expressed in renal oncocytomas and chromophobe renal cancers. S100A1 may further distinguish renal oncocytoma from chromophobe renal cancer. These markers will be analyzed by real time polymerase chain reaction (RT-PCR).