Differential diagnosis and evaluation of the incidentally discovered renal mass

Recent advances in technology, coupled with decreasing costs, have led to a substantial rise in the diagnosis of the incidentally discovered renal mass. In virtually all of these cases, the underlying signs and symptoms of an occult renal tumor were either absent or sufficiently minor as to escape the notice of the referring physician. Although the majority of the renal masses are benign renal cysts, many are indeterminate or frankly malignant. The evaluation of these tumors is typically completed with contrast-enhanced static or spiral computed tomography; however, ultrasound may be sufficient in many cases to definitively diagnose renal cysts. The size and location of these tumors often dictates treatment, and recently, less conservative management has found to be reasonably safe and effective. For instance, small localized tumors are now being considered for tumor enucleation, heminephrectomy or partial nephrectomy, even in the presence of an otherwise normal contralateral kidney. Recent innovations, including intraoperative sonography, have given the urologic surgeon an additional tool for complete evaluation of the indeterminate renal mass. These issues are discussed in detail, in order to achieve a rational approach to the differential diagnosis and evaluation of the incidental renal mass.