Your breasts are made up of connective tissues that include a system of milk ducts — tiny passages that carry milk to the nipples. Mammary duct ectasia occurs when a milk duct beneath the nipple widens, becoming blocked or clogged with a sticky substance and inflamed.

Experts don't know exactly what causes mammary duct ectasia. Some speculate the cause to be associated with:

  • Breast tissue changes due to aging. As you age, the composition of your breast tissue changes from mostly glandular to mostly fatty in a process called involution. These normal breast changes can sometimes lead to a blocked milk duct and the inflammation associated with mammary duct ectasia.
  • Smoking. Cigarette smoking may be associated with widening of milk ducts, which can lead to inflammation and, possibly, mammary duct ectasia.
  • Nipple inversion. A newly inverted nipple may obstruct milk ducts, causing inflammation and infection. A nipple that's newly inverted could also be a sign of a more serious underlying condition, such as cancer.
May 01, 2015

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