What is mammary duct ectasia?

Mammary duct ectasia is a noncancerous breast condition causing inflammation (swelling) and a thickening of the milk ducts. It is also known as duct ectasia or periductal mastitis.

Who is likely to have mammary duct ectasia?

Anyone can have mammary duct ectasia. The condition is more common among women who are approaching menopause. It can also occur after menopause.

What causes mammary duct ectasia?

Mammary duct ectasia results from inflammation (swelling). This inflammation causes a milk duct within the breast to widen and thicken. As inflammation worsens, milk ducts become blocked, and fluid builds up behind the blockage.

While the exact cause of this inflammation is unknown, researchers think that bacterial infection of the milk ducts make it more likely for a woman to develop mammary duct ectasia.

What are the symptoms of mammary duct ectasia?

For many women, periductal mastitis causes no symptoms. However, some women experience symptoms that can include:

  • Breast tenderness
  • Redness
  • Inverted nipple (nipple turning inward)
  • Thick nipple discharge that may be green or black

In a small number of women, mammary duct ectasia causes lumps to form in the breast. Lumps develop as a result of scar tissue that forms around inflamed milk ducts. The lump may be confused with breast cancer, but it is not cancer.

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