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 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:
May 01, 2015
- 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.
- Rosai J. Breast. In: Rosai and Ackerman's Surgical Pathology. Philadelphia, Pa.: Mosby Elsevier; 2011. https://www.clinicalkey.com. Accessed Feb. 5, 2015.
- Onstad M, et al. Benign breast disorders. Obstetrics and Gynecology Clinics of North America. 2013;3:459.
- Noncancerous breast conditions. American Cancer Society. http://www.cancer.org/healthy/findcancerearly/womenshealth/non-cancerousbreastconditions/non-cancerous-breast-conditions-duct-ectasia. Accessed Feb. 5, 2015.
- Dabbs DJ. Reactive and inflammatory conditions of the breast. In: Breast Pathology. Philadelphia, Pa.: Saunders Elsevier; 2012. https://www.clinicalkey.com. Accessed Feb. 5, 2015.
- Diagnosis of breast disease. Bloomington, Minn.: Institute for Clinical Systems Improvement (ICSI); 2012. https://www.icsi.org/_asset/v9l91q/DxBrDis.pdf. Accessed Feb. 5, 2015.
- Huttunen R, et al. Smoking and the outcome of infection. Journal of Internal Medicine. 2011;3:258. http://onlinelibrary.wiley.com/store/10.1111/j.1365-2796.2010.02332.x/asset/j.1365-2796.2010.02332.x.pdf;jsessionid=7E1BAE92F9DEA056669010BBC8721234.f03t01?v=1&t=i6ify7dg&s=582ed53a179e537e7c6ffffad0230dc4cbc1d013. Accessed Feb. 5, 2015.
- Pruthi S (expert opinion). Mayo Clinic, Rochester, Minn. Feb. 7, 2015.