Why Some People Have a Third Nipple

In This Article

Third nipples are common, though they often go undetected or are thought to be moles or birthmarks. They form during development in the uterus and may occur anywhere along the milk lines—the lines of potentially appearing breast tissue from just above the armpit to the groin. Most often, third nipples occur alone, but may sometimes be associated with congenital disorders of the heart or kidneys.

When an extra nipple (or nipples) occur alone, the condition is referred to as polythelia. When the third nipple is connected to breast (mammary) tissue and glands, it's called polymastia.

While third nipples don't increase the risk of breast cancer, they should be examined at the same frequency as normal breast tissue as they are susceptible to the same diseases. Removal isn't usually needed other than for cosmetic reasons or if the nipple causes discomfort, such as during breastfeeding.

Third nipples are sometimes referred to as:

  • Supernumerary nipples
  • Accessory nipples
  • Ectopic nipples
  • Triple nipples
  • Vestigial nipples
  • Witch's nipples

Types

There are six main categories of third nipples:

  • Category 1: A third nipple and areola is present with underlying breast tissue (polymastia).
  • Category 2: The third nipple doesn't have an areola, but does have underlying breast tissue.
  • Category 3: Breast tissue and an areola are present, but a nipple is not.
  • Category 4: Breast tissue is present, but there's no nipple or areola.
  • Category 5: A nipple and areola are present with fatty tissue beneath, but not breast tissue.
  • Category 6: A nipple is present without an areola or underlying breast tissue (polythelia).

In some cases, people have more than one third nipple (supernumary nipple) and these can be of different types.

Causes

Both men and women may develop an extra nipple, and they are medically considered to be a minor birth defect. It's a fairly common abnormality, one that affects roughly one in 20 people.

Third nipples sometimes occurs in families, but are more likely to be a random phenomenon. Some cases are linked to other birth defects (congenital disorders) involving the heart or kidneys.

A possible link between supernumary nipples and BRCA2 gene mutations was proposed in a 2017 study in which a brother and sister both had breast cancer, BRCA2 mutations, and bilateral supernumary nipples. While an association is unknown at this time, those who have third nipples may consider asking their relatives about the presence of third nipples or any genetic testing for cancer risk they have done.

Genome wide association studies in other species (sheep) have found loci in DNA that are associated with the development of supernumerary nipples, but thus far an association in humans has not yet been studied.

How They Form

The breasts form early on in an embryo's development, typically during the fourth week of gestation. Milk lines, the first evidence of mammary gland development, appear soon after, at around the sixth week of development. These ridges arch down from the armpit to the groin on both sides of the body. As the breasts continue to develop, these lines eventually disintegrate, usually by about week nine. 

Occasionally, however, milk lines will persist and may be connected to extra breast tissue and extra nipples. Extra nipples that are connected to breast tissue may sometimes produce breast milk after pregnancy.

Supernumerary nipples are usually smaller than regular nipples.

Scaramanga, an infamous Bond villain, had an accessory nipple, and this was what made him easy to identify. Scientists named the Scaramanga gene after him; it's this gene that produces a protein called neuregulin-3 (NRG3), which provides a signal to embryonic cells telling them to become breast cells.

Breast Cancer Risk

If you have one or more extra nipples, you may wonder if this increases your risk for breast cancer. Any breast tissue you have, whether it appears in the standard location or elsewhere, is vulnerable to the same diseases that can affect typical breast tissue.

Extra nipples that occur alone (are not attached to breast tissue) may uncommonly be affected by a cancer of the nipples known as Paget's disease of the nipple. Paget's can sometimes also show up in the groin area (lower end of the milk lines), where it is called extramammary Paget's disease (EMPD).

When to See Your Doctor

In most people, extra nipples are benign and—because they often occur below the breast—may never be noticed. But if you know you have a third nipple, talk to your doctor if you note any changes such as dryness or flakiness, a rash, or a lump.

Not all nipple changes indicate breast cancer, but knowing which are expected changes and which are signs of disease is critical to your breast health.

Genetic Testing

Now that genetic testing is available for some familial breast cancers, it's important for people to be aware of third nipples (at least those associated with breast tissue), as these areas will need to be monitored along with the two "normal" breasts, and considered when developing any treatment plans.

Removal

Third nipples don't usually need to be removed, but sometimes people wish to have them removed for cosmetic reasons or if they cause discomfort. Surgical procedures will vary depending on whether or not the third nipple is associated with underlying breast tissue.

Isolated third nipples can be removed via a simple procedure, similar to the removal of a mole. For supernumerary nipples connected with breast tissue, a mastectomy (removal) can be done.

A Word From Verywell

Third nipples are common, but often go undetected or are thought to be moles. Most often, they're not associated with any underlying problems and don't need any special attention. But if you believe you may have an extra nipple it's important to bring it to your doctor's attention.

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  1. McKay M, Coad R. A brother and sister with breast cancer, BRCA2 mutations and bilateral supernumerary nipples. Annals of Translational Medicine. 2017. 5(5):106. doi:10.21037/atm.2017.03.02

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