The presence of a third or extra nipple is a relatively common congenital variation, often referred to as a supernumerary or accessory nipple. This anatomical feature is formed during embryonic development and is typically a benign finding that many people may not even realize they have. The condition represents a minor anomaly in the body’s formation process and does not usually indicate any serious underlying health issue. Understanding this variation involves looking at its definition, its prevalence in the general population, and the circumstances under which it might warrant medical attention.
What Defines an Accessory Nipple
An accessory nipple develops when the ectoderm tissue, which forms the skin, fails to fully regress along the embryonic milk line. This “milk line” is a pair of thickened epidermal ridges that run vertically on each side of the body, extending from the armpit down to the groin. The extra tissue can appear anywhere along this path, though it is most frequently found below the existing breasts. Clinical terminology distinguishes between two forms of the condition based on the tissue present. Polythelia describes an accessory nipple consisting only of nipple tissue, while polymastia refers to the much rarer presence of a fully developed accessory breast, complete with glandular tissue. Variations exist on a spectrum, ranging from a simple patch of hair to a small, raised area that resembles a mole or a birthmark.
How Common Is This Anatomical Variation
Accessory nipples are more common than many people assume, though prevalence estimates vary significantly depending on the study population and methodology used. Data suggests that this anatomical variation occurs in approximately 1% to 5% of the general population. Some studies report rates as low as 0.22% in certain European populations, while others find rates up to 6% in specific ethnic groups or geographic regions. This wide range often reflects the difficulty in identifying the condition, as many accessory nipples are quite small and underdeveloped. They are frequently mistaken for moles, freckles, or simple birthmarks, causing them to go undiagnosed throughout a person’s life.
When Medical Consultation Is Necessary
For most people, an accessory nipple is merely a cosmetic concern and does not require medical intervention. However, accessory breast tissue can be susceptible to the same hormonal changes as normal breast tissue, and it can sometimes become symptomatic. A medical consultation is recommended if the accessory nipple tissue begins to change, such as becoming painful, tender, or swollen, particularly during menstruation, pregnancy, or lactation. A doctor should also evaluate the area if any physical changes occur, including the development of hardened tissue, new lumps, a rash, or any abnormal discharge from the nipple. While rare, extra breast tissue is vulnerable to the same pathologies as a normal breast, including cyst formation or malignancy, which makes monitoring any changes important.