Bosniak Classification

Silverman SG, Pedrosa I, Ellis JH, et al. Bosniak Classification of Cystic Renal Masses, Version 2019: An Update Proposal and Needs Assessment. Revised the original CT-only classification to also apply to MRI, refined the category definitions to reduce inter-reader variability, and gave the approximate malignancy risk per category used here.

I and II are followed as any other benign finding; IIF is followed with periodic imaging (surveillance protocols vary by institution); III and IV are usually referred for surgery or ablation, though active surveillance can be appropriate for III in a patient whose comorbidities or life expectancy favour it, by shared decision with urology.