Category Migration of Renal Cystic Masses with Use of Gadolinium-Enhanced Magnetic Resonance Imaging

Abstract
The Bosniak renal cyst classification has been accepted by urologists and radiologists as a way of diagnosing cystic renal masses and determining the management approach. We report two cases of a renal cystic mass that showed a category change from category II on the basis of enhanced computed tomography to category IV after further gadolinium-enhanced magnetic resonance imaging. In both cases, the cysts were later confirmed as kidney cancer by pathology.