Unlike some other organs, like the liver, the spleen does not grow back (regenerate) after it is removed. Up to 30% of people have a second spleen (called an accessory spleen). These are usually very small, but may grow and function when the main spleen is removed.

How common is an accessory spleen?

Accessory spleens are found in approximately 10–30% of patients. Most patients are asymptomatic, with accessory tissue found incidentally or described on autopsy studies [1].

Is an accessory spleen harmful?

Multiple (accessory) spleens do not cause medical problems, and nothing is done about them. Rarely, accessory spleens may be confused with tumors. They usually can be definitely identified by radionuclide liver-spleen scans.