Mammary duct ectasia (ek-TAY-zhuh) occurs when a milk duct beneath your nipple becomes wider (dilated), the duct walls thicken and the duct fills with fluid. The milk duct can then become blocked or clogged with a thick, sticky substance. The condition often causes no symptoms, but some women may have nipple discharge, breast tenderness or inflammation of the clogged duct (periductal mastitis).
Your chance of developing mammary duct ectasia — with or without inflammation — increases with age. Mammary duct ectasia usually improves without treatment. However, if symptoms persist despite self-care measures, you may need antibiotics or possibly surgery to remove the affected milk duct.
Though it's normal to worry about any changes in your breasts, mammary duct ectasia and periductal mastisis aren't risk factors for breast cancer.