Many people have an anatomical variation commonly known as a “third nipple,” or medically termed a supernumerary nipple. This condition represents a relatively common and usually harmless congenital variation. It is a natural aspect of human development, often going unnoticed due to its varied appearance.
Understanding Supernumerary Nipples
Supernumerary nipples are extra nipples or associated tissue that develop in addition to the two typical nipples. They form during embryonic development along what is known as the “mammary ridge” or “milk line.” This ridge is a thickened strip of tissue that extends from the armpit down to the groin area on both sides of the body. While breast tissue normally develops only in the chest region, incomplete regression of this mammary ridge during development can lead to the formation of extra nipples anywhere along this line, and sometimes even beyond it.
These extra nipples present in a range of forms, from a fully developed extra breast with glandular tissue (polymastia) to simply a patch of hair. They can appear as only a nipple (the most common type), an areola, or a small bump resembling a mole or freckle. They are present at birth, though they may become more apparent later in life due to hormonal changes.
Prevalence of Supernumerary Nipples
Supernumerary nipples are more common than many realize, with estimates ranging from 1% to 6% of the global population. Prevalence varies by ethnicity, sex, and geographical region. For instance, studies show prevalence of 1.63% in African American neonates, 2.5% in Israeli neonates, and up to 5.6% in German children. Conversely, white Europeans have a reported prevalence as low as 0.22%.
Some data suggest that supernumerary nipples might be slightly more prevalent in males than females, and a higher incidence has been observed on the left side of the body. Despite these variations, it remains a relatively frequent anatomical characteristic across diverse populations.
Health Considerations
Supernumerary nipples are generally benign and do not pose a health risk. However, because they consist of mammary tissue, they can respond to hormonal fluctuations in a similar manner to typical nipples. This means they may become more noticeable, swell, or become tender during puberty, menstruation, or pregnancy. In some instances, if they contain glandular tissue, they can even produce milk during lactation.
While typically harmless, there have been rare reports of supernumerary nipples being associated with other medical conditions. These associations are considered rare occurrences, and for most individuals, a supernumerary nipple is simply a cosmetic variation. Surgical removal is an option for individuals who experience discomfort, irritation, or have cosmetic concerns. If any unusual changes, such as new lumps, hardening, rash, or discharge, occur, consulting a healthcare provider is advisable for evaluation.