Simple kidney cysts are abnormal pouches containing fluid. The simple cyst is the most common form. Although its cause is not fully understood, we do know that the simple cyst is not an inherited condition. Single or multiple cysts may develop on small tubes in the kidneys.

Most often, simple cysts do not cause symptoms or harm the kidney. In some cases, however, pain can occur when cysts enlarge and press on other organs. Sometimes cysts become infected or suddenly start to bleed. Less often the cysts impair kidney function. Simple cysts can also cause high blood pressure.