Milk tissue in the armpits

What are these big lumps in my armpits?

Some women have milk tissue in their armpits. In fact, milk tissue can be found anywhere along the “milk line,” which runs from the armpit to the groin. In rare cases it can be found elsewhere on the body. Milk tissue in the armpits and elsewhere behaves like milk tissue in the breast and responds to pregnancy and delivery by growing and making colostrum and milk. Milk tissue in the armpit can form grapefruit-sized lumps that may be tender. Cold compresses can decrease the swelling and non-prescription medication can ease the pain. This condition settles within a few weeks after birth. The armpit tissue stops making milk and the milk that was produced is absorbed into the body. 

A) Milk tissue located away from the breast

Breast tissue in the armpits one week after delivery.

Tissue that makes milk is usually found in the breast, but it can be found away from the breast (ectopic). Most ectopic breast tissue is found along the “milk line,” which goes from the armpit to the groin. In very rare cases, it is found in other places such as the back, face, foot, or the genital area (Mayer 2019; Thiryayi 2019).

An estimated 2% to 6% of women have ectopic milk tissue (Patel 2012). This can also develop in men but is less common (Burdick 2003).  

Ectopic milk tissue responds to the woman’s hormones, growing with puberty and pregnancy, and even making colostrum and then milk. This can cause tenderness.  

Problems that arise in the breast may also be found in milk tissue that is not in the breast. These include (Farrokh 2017; Khan 2019; Khanna 2015; Mandal 2020; Patel 2012; Sanguinetti 2010; Soares 2013):  

  • Mastitis
  • Abscesses
  • Cysts
  • Benign tumours
  • Cancer

B) Ectopic breast tissue in the armpit

Breast tissue in the armpits one week after delivery.

1) Behaviour 

Ectopic milk tissue in the armpits can grow significantly during pregnancy and even dramatically when the milk comes in. Some new mothers have grapefruit-sized lumps that prevent them from putting their arms down by their sides. The lumps may be moderately tender. 

2) Treatment

Cold compresses such as green cabbage leaves, which are used for engorgement, can help decrease swelling but are hard to keep in place. Non-prescription pain medication can also be used.

Milk tissue in armpits is unconnected to milk ducts in the breast. This means that breastfeeding and expressing will not shrink the lumps.

Some mothers have a nipple in the armpit that leaks milk. This may help drain the milk tissue and ease the discomfort. Massaging the lump toward the armpit nipple with the fingers and a little bit of cooking oil may further help the tissue drain. In general, only small amounts of milk can be removed this way, which limits its usefulness.

The good news is that this condition settles within a few weeks after birth. Unlike the milk tissue in the breast, which is regularly emptied by breastfeeding, armpit milk tissue is not emptied and will stop making milk in a few weeks. Any milk present will be absorbed into the body. 

3) Long-term management

If you have milk tissue in the armpit, make sure you tell the people doing your breast cancer tests (mammograms) so it is not missed during an examination.

Sometimes this tissue, along with any excess skin, is removed by surgeons.This can be for medical concerns, to prevent skin irritation, because of difficulty moving the arm and pain with periods, or for cosmetic reasons (Aydogan 2010).

C) Nipples located away from the breast

Extra nipples may form along the milk line in both women and men. These are not uncommon and tend to run in families. They are most commonly found on the upper part of the tummy or in the armpit. They may or may not have associated milk tissue.


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