Primarily imaging studies USG, CT SCAN, MRI are used to differentiate malignant from benign lesions. BIOPSIES ARE RARELY CARRIED OUT FOR RENAL MASSES
Unless clear criteria for benign masses are met on the above tests ;for example, presence of fat in angiomyolipoma or lack of contrast enhancement on a CT scan for solid benign masses;WE TREAT RENAL MASSES AS MALIGNANT . A vast majority of renal masses are diagnosed after definitive surgical treatment which is removal of the mass