CT and MR of Atypical Cystic Renal Masses: Revisiting the Bosniak Classification

Abstract

Advances in cross-sectional imaging techniques, especially ultrasound, CT, and MRI, have allowed the frequent detection and more detailed characterization of renal cystic masses. Benign renal cortical cysts, the most common renal masses, usually demonstrate classic features on cross-sectional studies. When complicated by hemorrhage or infection, however, these lesions defy diagnosis because of overlap in the imaging appearances of benign and malignant cystic lesions. The application of proper CT technique, combined with the use of ultrasound and MRI when indicated, allows the radiologist to accurately characterize these complex renal cystic lesions and facilitate appropriate therapy.