What is (are) Simple Kidney Cysts ?
Simple kidney cysts are abnormal, fluid-filled sacs that form in the kidneys. Simple kidney cysts are different from the cysts that develop when a person has polycystic kidney disease (PKD), which is a genetic disorder. Simple kidney cysts do not enlarge the kidneys, replace their normal structure, or cause reduced kidney function like cysts do in people with PKD.
                
Simple kidney cysts are more common as people age. An estimated 25 percent of people 40 years of age and 50 percent of people 50 years of age have simple kidney cysts.1