A related condition, in which extra nipples form, is called "supernumerary nipple" or "polythelia".
It was once believed that polymastia results from the eruption of extra breasts along the milk line during embryonic development. However, this theory is not generally believed today and cannot account for the appearance of nipples that do not correspond to the milk line's pathway. In unusual cases, extra breasts may appear on the buttock, the back of the neck, the face, the upper arm, the shoulder, the hip, or the back. In one case one developed on the underside of a woman's foot.
Polymastia is often associated with abnormalities of the urinary tract and with certain diseases.
Anne Boleyn, second wife to Henry VIII of England, and mother of Elizabeth I, may have had a third nipple or even a third breast. (This may well have been a slanderous rumour, as in Tudor times these "malformations" were considered to be a sign of the owner being a witch. The circumstances of her marriage to the king, who had divorced his first wife, made her a controversial figure.)
In popular culture and fiction
In mythology, attributes are exaggerated or multiplied to emphasize their efficacy. For example, Priapus has been depicted with an oversized penis, and Artemis of Ephesus has been portrayed as having tier upon tier of what may be breasts, as tradition has it, or sacrificed bull testes, as some newer scholars claim. Priapus' gigantic phallus underscores his virility and his fertility, while Artemis' tiers of breasts, if so they are, would highlight her ability to nurture.
Accessory breasts and supernumerary nipples have often been the subject of popular speculation and urban legend.
The additional-breast motif has also been used in motion pictures, TV shows, novels and other works of fiction:
- (1978) In The Hitchhiker's Guide to the Galaxy novel series, Eccentrica Gallumbits, the Triple-Breasted Whore of Eroticon 6, is a frequently alluded-to character.
- (1982) The film The Sword and the Sorcerer features a dancer with two breasts in the normal positions and a third centered below them.
- (1983) A six-breasted dancer, Yarna d'al' Gargan, appears in Star Wars Episode VI: Return of the Jedi.
- (c. 1983) In the Warhammer Fantasy and Warhammer 40,000 universes, daemonettes (female demons) of the god Slaanesh have six breasts: two pairs of smaller breasts below their "normal" breasts along the milk lines. Previous depictions of daemonettes have also featured three breasts.
- (1984) A similar fantasy filmic exotic dancer in The Warrior and the Sorceress has four breasts, two appearing below the regular pair.
- (1990) The movie Total Recall features a mutant prostitute with three side-by-side breasts (a likely homage to Eccentrica Gallumbits, above).
- (1998) In the video game Parasite Eve, the antagonist, Mitochondria Eve, is shown with multiple breasts at one point in the game.
- (2002) Whoa, a character in the movie Kung Pow! Enter the Fist had only one breast.
- (2002) In the Adam Sandler movie Eight Crazy Nights, a woman has three breasts.
- (2002) The song "Year 3000" by British band Busted (later covered by the Jonas Brothers) features the line "Triple-breasted women swim around totally naked."
- Conde, Délio Marques. "Pseudomamma on the foot: An unusual presentation of supernumerary breast tissue". Dermatology Online Journal. 12 (4): 7. Unknown parameter
- PMID 11500714
- , PMID 10653061