Small renal masses (lesions smaller than 3 cm): imaging evaluation and management

The current use of CT and sonography for a wide variety of indications has led to the frequent incidental discovery of small (1.5-3.0 cm) and very small (< 1.5 cm) lesions in the renal parenchyma. These lesions are usually small benign cysts, complicated cysts, or small neoplasms. Although the increased sophistication of imaging technology has certainly improved the detection of these lesions, a specific diagnosis can be elusive, and management is controversial. The question remains as to whether lesions that prove to be neoplasms warrant treatment or whether they are clinically insignificant and should be ignored. The radiologist plays a major role in making this decision. The purpose of this article is to review the literature regarding the etiology and imaging evaluation of small renal lesions and to make recommendations for their appropriate management.