Accessory breast

Accessory breast
A woman with several accessory breasts
Specialty Medical genetics

Accessory breasts, also known as polymastiasupernumerary breasts, or mammae erraticae, is the condition of having an additional breast. These extra breasts may appear with or without nipples or areolae. 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.

A related condition, in which extra nipples form, is called “supernumerary nipple” or “polythelia”.

Presentation

In some cases, the accessory breast may not be visible at the surface. In these cases, it may be possible to distinguish their appearance from normal breast tissue with MRI.[1] In other cases, accessory breasts have been known to lactate, as illustrated in a drawing showing a child nursing at ectopic breast tissue on the lateral thigh.[2]

A woman with a lactating supernumerary breast on her thigh

There is some evidence that the condition may be more common in Native American populations.[3]

Cause

Polymastia typically occurs in the womb during development. During normal development, breast tissue will develop along the milk line, and additional tissue will disintegrate and be absorbed into the body. Polymastia occurs when the additional tissue does not disintegrate before birth. This condition can be inherited.