The incidence of simple renal cyst by computed tomography.

Five hundred and forty-two abdominal computed tomography (CT) scans, including the kidneys, were reviewed to investigate the incidence of simple renal cysts. Increasing frequency with age was clearly demonstrated. The incidence in patients 50 years of age and over was at least 27%. Two thirds of simple renal cysts were 2 cm or less in diameter. Cysts were usually observed as exo-endoparenchymal or endoparenchymal lesions on CT.