A supernumerary nipple, formally known as polythelia, is the presence of an extra nipple. This minor congenital anomaly is present from birth and is more common than many realize. While the condition can lead to questions about its nature and health implications, it is overwhelmingly a benign physical variation.
Understanding Supernumerary Nipples
The biological explanation for an extra nipple lies in the body’s embryonic development. During the fourth week of gestation, an embryo forms two thickened strips of tissue called the mammary ridges, often referred to as the “milk lines.” These ridges extend from the armpit area down to the groin region. Normally, these ridges regress almost completely, leaving behind only the two spots where the primary breasts develop.
A supernumerary nipple forms when a small segment of this embryonic tissue fails to fully disappear, causing it to persist into adulthood. The extra tissue can develop into a structure that contains any combination of the components that make up a regular breast: the nipple, the areola, or glandular tissue. The prevalence of this occurrence is estimated to affect between 0.2% and 6% of the general population.
Identifying the Different Types
Visually identifying a supernumerary nipple requires looking for specific characteristics, most importantly its location along the milk line. This imaginary line runs vertically on the front of the body, starting in the armpit and extending down through the typical nipples and ending near the inner thigh. While most extra nipples are found along this path, some rare cases occur in other locations, which are termed ectopic.
The appearance of these structures varies significantly and is categorized into eight types based on the tissues present. The most common form is polythelia, a small, elevated structure that resembles a nipple but lacks an areola or underlying glandular tissue. This small bump can often be mistaken for a slightly raised mole or a pigmented freckle because it is typically much smaller than a standard nipple.
Another common form is polythelia areolaris, where only a patch of pigmented skin, similar to an areola, is present without a distinct nipple projection. To distinguish a supernumerary nipple from a mole or a skin tag, note that moles and skin tags generally do not have the ridged texture or the smooth muscle and pilosebaceous follicles found in nipple tissue. Furthermore, supernumerary nipples may become more noticeable, darken, or develop a fine patch of hair during hormonal changes like puberty or pregnancy. The most complete form, known as polymastia, includes the presence of a nipple, areola, and functional glandular tissue underneath, making it look like a miniature extra breast.
Medical Significance and When to Seek Consultation
For the vast majority of people, the presence of a supernumerary nipple is a benign finding that poses no health risk and is purely a cosmetic concern. These accessory structures are usually asymptomatic, meaning they do not cause any pain or discomfort. However, in cases where glandular tissue is present, the supernumerary nipple can react to hormonal fluctuations, potentially becoming tender or slightly swollen during a menstrual cycle or even producing milk during pregnancy.
There has been historical discussion about a possible association between supernumerary nipples and underlying health conditions, particularly anomalies of the urinary tract or kidneys. Current research on this connection provides conflicting results. The presence of an extra nipple alone in an otherwise healthy individual is generally not considered sufficient reason to screen for internal organ issues. The rare instances of associated conditions are typically seen when the supernumerary nipple occurs alongside other minor congenital anomalies or genetic syndromes.
You should consult a dermatologist or primary care physician if the tissue begins to change appearance, becomes tender, or starts to discharge fluid without an obvious hormonal cause. Any sign of growth, change in color or shape, or the development of a lump within the tissue warrants a medical evaluation, as the glandular tissue in a supernumerary breast is susceptible to the same diseases, including cancer, as a typical breast. If the extra nipple causes persistent irritation due to clothing or if you are concerned about its appearance, a healthcare professional can discuss removal options.