CausesBy Mayo Clinic staff
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 becomes wider (dilated), 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 blockage of a 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 also could be a sign of a more serious underlying condition, such as cancer.
- Non-cancerous breast conditions. American Cancer Society. http://www.cancer.org/acs/groups/cid/documents/webcontent/003180-pdf.pdf. Accessed April 24, 2012.
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- Understanding breast changes: A health guide for women. National Cancer Institute. http://www.cancer.gov/cancertopics/screening/understanding-breast-changes/page1/AllPages. Accessed April 24, 2012.
- Rosen PP. Rosen's Breast Pathology. 3rd ed. Philadelphia, Pa.: Lippincott Williams & Wilkins; 2009:33.
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- Pruthi S (expert opinion). Mayo Clinic, Rochester, Minn. May 10, 2012.