Simple liver cysts — fluid-filled cavities in the liver — usually cause no signs or symptoms and need no treatment. However, they may be large enough to cause pain or discomfort in the upper right part of the abdomen. Most liver cysts can be detected on ultrasound or computerized tomography (CT) scans. When needed, treatment may include drainage or removal of the cyst. The cause of simple liver cysts isn't known, but they may be the result of a malformation present at birth. Rarely, liver cysts may indicate a serious, underlying condition such as: Polycystic liver disease, an inherited disorder.