The condition, a form of atavism, is most commonly observed in males and is generally harmless, often going untreated.

However, in recent years, many affected women have had a plastic surgery operation to remove the additional breasts, for purely aesthetic reasons.

In these cases, it may be possible to distinguish their appearance from normal breast tissue with MRI.

[2] There is some evidence that the condition may be more common in Native American populations.

Polymastia occurs when the additional tissue does not disintegrate before birth.