Ultrasound of Renal Masses.

Renal masses are common incidental findings. Although most are benign, it is important to evaluate for features concerning for malignancy. Because of its relative low cost; excellent differentiation among simple cysts, complex cysts, and solid lesions; and lack of ionizing radiation, ultrasound is the preferred modality for initial workup of renal lesions. Given the increasing availability of contrast-enhanced ultrasound, more and more lesions are now able to be completely characterized by sonography alone, including use of the Bosniak criteria.