[Characterization of complex renal cysts].

Complex renal cysts represent a clinical problem, since it is often difficult to exclude malignancy. The Bosniak classification uses computed tomography (CT) to categorize cystic renal lesions. Category I and II are presumed to be benign, and III and IV potentially malignant. Category IIF cysts are lesions that may develop into malignancy. Studies exploring whether the IIF category solves the clinically important problem of differentiating between benign and malignant cysts are needed.