Urological Survey 790 features and a malignant or benign diagnosis. The sensitivity, specificity, and positive and negative predictive values of progressive enhancement for a diagnosis of benignity were 60%, 73%, 43%, and 84%. Conclusion: In the evaluation of enhancing small solid renal lesions without fat, no CT criteria were of substantial help in differentiating malignant from benign lesions. Editorial CommentPre-operative characterization of small solid enhancing renal lesion containing no macroscopic fat is a difficult task. Although the CT characteristics of benign solid renal lesion overlap with those of renal cell carcinoma, we encourage radiologists from our institution to narrow the differential diagnosis whenever it is possible. The pre-operative radiologic impression of renal tumor histology is of particular value when affects therapeutic management. During the nephrographic (90-100 seconds) and excretory phase (180 seconds), some renal tumors subtypes demonstrate significant different degrees of enhancement. Clear cell of renal carcinoma can be suggested by the presence of strong and heterogeneous contrast enhancement and rapid washout. Papillary renal cell carcinoma is usually homogeneously hipovascular similarly to the rare benign metanephric adenoma. Solid homogeneously hypervascular renal mass can be observed in oncocytoma and angiomyolipoma without macroscopic fat. Thus, depending on the clinical scenario, percutaneous biopsy is performed particularly when its results will influence therapeutic management