Kidney cysts

Kidney cysts are fluid-filled sacs that form in the kidneys. They're almost always noncancerous (benign). The most common type is a simple kidney cyst, also called an acquired simple cyst. Up to half of people older than age 50 have at least one kidney cyst.

Small kidney cysts typically cause no signs or symptoms. They're often found incidentally on a computerized tomography (CT) scan, magnetic resonance imaging (MRI) exam, or ultrasound of the kidneys done for some other reason. Kidney cysts usually need no treatment. However, some become so large that they press on other organs and require surgical removal.

Other kidney cyst disorders include polycystic kidney disease and multicystic kidney dysplasia. Although rare, these disorders can eventually lead to kidney failure.