Doctors discovered milk in the armpit of a woman who gave birth – they explain the rare condition

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  • A 26-year-old Portuguese woman started experiencing pain in her armpit shortly after giving birth.
  • Upon examining her, doctors found she had accessory breast tissue, medically known as polymastia.
  • When they pressed around the region, a white discharge was released, which they realised was breast milk.

Pregnancy and childbirth can transform the body in fascinating ways, but for one woman from Portugal, an unexpected change caught her by surprise.   

According to a report published in The New England Journal of Medicine, a 26-year-old woman started feeling pain in her armpit two days after giving birth.

Describing the case, doctors from the Hospital de Santa Maria in Lisbon examined the area and found a round mass. Upon pressing it, a white discharge was released, which they realised was breast milk. They concluded that it was consistent with polymastia, a condition where extra breast tissue develops in the body. 

They explained: “In the postpartum period, milk can drain from the tissue, which may become enlarged, in some instances causing pain and discomfort.” 

The authors explained that the condition was benign (not harmful). However, patients with polymastia are strongly advised to have the tissue examined and screened for breast cancer.

Their report did not mention whether the patient could breastfeed or pump milk from the accessory tissue.

Doctors found a mass in the patient's right armpit. Image: Dr Marinho-Soares, Dr Pulido-Valente, NEJM
The patient was found to be lactating from her armpit. Image: Dr Marinho-Soares, Dr Pulido-Valente, NEJM

How common are 'accessory breasts'?

About 2% to 6% of females are affected by polymastia, according to a separate study published in 2012.

Some women who develop polymastia but do not have a nipple or areola (the pigmented skin surrounding the nipple), may never realise they have accessory breast tissue, unless they become pregnant or start breastfeeding, explained the authors of a paper published in Mayo Clinic Proceedings in 1999.

The 2012 study also noted that ectopic (in an unusual place) breast tissue may develop in locations such as the face, back, and thigh. 

Symptoms of polymastia

Symptoms generally include swelling and tenderness of the affected region, thickening of the armpit and part of the shoulders, as well as irritation from clothing. Puberty and pregnancy can worsen the onset of these symptoms, the researchers said.

Although there are a number of treatments to correct accessory breast tissue, it is generally recommended that it be surgically removed, the authors wrote.

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