OVERVIEW: The incidental renal mass represents a heterogeneous group that contains both benign and malignant pathologies. The majority of renal cell carcinomas are discovered incidentally, without the presence of symptoms directly related to the mass, and are closely associated with the term small renal masses because of the discovery before the onset of symptoms. In general, small renal masses are defined as 4 cm or smaller, and may account for greater than half of renal cell carcinoma diagnosis. The use of renal mass biopsy may offer additional pathological information but the clinician must be reminded of the technical and diagnostic limitations of renal mass biopsy. Patient-dependent factors, such as life expectancy and comorbidities, guide the management of small renal masses, which include active surveillance, partial nephrectomy, radical nephrectomy, and ablative techniques (cryoablation and radiofrequency ablation). Partial nephrectomy has demonstrated durable oncologic control for small renal masses while preserving renal function and, if feasible, is the current treatment of choice. In the other extreme of the renal cell carcinomas spectrum and in the presence of metastatic disease, the removal of the renal primary tumor is termed cytoreductive nephrectomy. Two randomized trials (SWOG 8949 and EORTC 30947) have demonstrated a survival benefit with cytoreductive nephrectomy before the initiation of immunotherapy. These two studies have also been the motivation to perform cytoreductive nephrectomy in the targeted therapy era. Currently, there are two ongoing randomized prospective trials accruing to investigate the timing and relevance of cytoreductive nephrectomy in the contemporary setting of targeted therapy.
Differentiation of Small Renal Masses of 4cm or less between Renal Cell Carcinoma and Cysts using Attenuation Values on Unenhanced Computerized Tomography
