Overview

Mammary duct ectasia (ek-TAY-zhuh) is a noncancerous breast condition that affects the tubes that carry milk, called the milk ducts. It happens when one or more milk ducts beneath your nipple widen, thicken and fill with fluid. This can cause the milk ducts to become blocked or clogged with a thick, sticky substance that often is yellow or green in color.

Mammary duct ectasia often has no symptoms. But some people may have:

  • Nipple discharge.
  • Breast tenderness.
  • Inflammation of the clogged duct, which is called periductal mastitis.

Mammary duct ectasia most often happens during perimenopause, around age 45 to 55. But it also can happen after menopause. The condition often gets better without treatment. If symptoms don't go away, you may need antibiotics or possibly surgery to remove the clogged milk duct.

Although changes in your breasts may seem concerning, mammary duct ectasia and periductal mastitis aren't risk factors for breast cancer. It's a good idea to talk with your healthcare professional about any changes in your breasts.

Illustration of clogged milk duct in mammary duct ectasia

Mammary duct ectasia

Mammary duct ectasia happens when one or more milk ducts beneath the nipple becomes wider. This is called a dilated milk duct. The duct may fill with fluid and become blocked or clogged with a thick, sticky substance. Mammary duct ectasia often causes no symptoms, but some people may have nipple discharge, breast tenderness or inflammation of the clogged duct.


Symptoms

Mammary duct ectasia often doesn't cause any symptoms. People with symptoms may have:

  • A dirty white, yellow, green or black nipple discharge from one or both nipples.
  • Tender breasts or nipples.
  • A change in color of the nipple and surrounding skin, called the areola. This change may be a shade of red, purple or brown, depending on your skin color.
  • A breast lump or thickness near the clogged duct.
  • A nipple that's turned inward, also called inverted.

Sometimes, a blocked milk duct gets infected. This is called mastitis. Mastitis can cause breast tenderness, inflammation in the areola and fever.

Symptoms of mammary duct ectasia may get better on their own.


When to see a doctor

Make an appointment with your healthcare professional if you notice changes in your breasts that don't go away or that worry you. Some things to watch for are a new breast lump, sudden nipple discharge, a change in skin color, skin swelling or irritation, or an inverted nipple.

Illustration of an inverted nipple

Inverted nipple

A nipple that's always been turned inward, also called inverted, usually isn't a medical concern. But a nipple that is newly inverted should be checked by a healthcare professional.


Causes

Experts don't know exactly what causes mammary duct ectasia. The condition may be related to changes in the breast tissue. Your breasts are made up of connective tissues that have tiny tubes inside called milk ducts that carry milk to your nipple. Mammary duct ectasia happens when a milk duct beneath the nipple widens, which often happens with age. The duct walls may thicken and fill with fluid, becoming blocked or clogged with a sticky substance. This can cause painful swelling, called inflammation.


Complications

Usually, the complications of mammary duct ectasia aren't serious, but they can be bothersome. They may include:

  • Nipple discharge. Nipple discharge caused by mammary duct ectasia can be frustrating. Fluid leaking from your nipples can cause embarrassing wetness and stains on your clothes.
  • Breast pain. Mammary duct ectasia can cause swelling and tenderness around your nipples.
  • Infection. An infection may develop in the clogged milk duct. This can cause pain in or around the nipple, a sick feeling, or a fever. Lasting skin color changes and pain that's getting worse could be symptoms of a bacterial infection. A bacterial infection may lead to a collection of pus in your breast tissue. This is called an abscess. A procedure may be needed to drain the abscess.
  • Concern about breast cancer. When you notice a change in your breast, you may worry that it's a sign of breast cancer. This may be especially true if you have a hard lump around the nipple or areola. Having mammary duct ectasia doesn't increase your risk of breast cancer. Still, it's important to see your healthcare professional soon anytime you notice breast changes.

September 05, 2025

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