Liver cysts are common incidental findings on routine ultrasound scan of the abdomen. In general, small and simple liver cysts are benign and need no intervention. In fact, such cysts are also commonly found in the kidneys and occasionally in the pancreas.
If your mom's liver function test is normal and she does not have other liver related problems such as viral hepatitis, there is very little you need to worry about.
Although the liver cysts may grow in size slowly and more cysts may be found over time, most patients remain healthy throughout. She can keep a watch by repeating her liver function and ultrasound scan say in a year's time.
One ward of caution is the present of cysts with complex internal wall or structures or cysts which grows quickly. Such cysts may not be entirely friendly and carry the risk of transformation to something nasty over time. In such a case, surgical resection may be an option to consider.
-Dr Quan