An Overview of Adenosis of the Breast

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Adenosis of the breast is a condition in which the milk-producing lobules in the breast become enlarged and glands may increase in number. This is a benign condition, meaning it is not cancerous. It may be noted during a breast self-exam or during a screening mammogram, the X-ray test that looks for suspicious areas in the breasts.

This article will review symptoms of adenosis of the breast, how it is diagnosed, and how it is treated.

Adenosis may show up on a mammogram as a mass or calcification (small white calcium deposits), both of which are typical signs of breast cancer. Although some research indicates that adenosis, specifically the sclerosing type that causes scar-like fibrous tissue, may offer some increased risk for breast cancer, the condition itself is not cancerous.

Adenosis lumps mostly affect premenopausal women and may not necessarily require treatment. 

Also Known As

Adenosis in the breast is also called mammary adenosis, aggregate adenosis, tumoral adenosis, or adenosis tumor.


Adenosis may not be detectable during a breast self-exam or a clinical breast exam, because it may be small and not near the surface of the skin. Adenosis is more likely to be detected in these ways when there are several lobules in a group. To the touch, this lumpy area can feel like a cyst, fibroadenoma (a type of benign breast tumor), or a cancerous tumor.

The most general characteristics of adenosis are:

  • Periodic pain and swelling in the breast(s): The pain level and frequency may increase at certain times of your menstrual cycle. 
  • Breast engorgement: This symptom also seems to change during a woman’s menstrual cycle.
  • A benign lump in a single breast: The lump is usually painless and, while typically small, may be felt. It may have a nodular (mass-like) appearance. Sometimes, lumps may occur in both breasts.

Adenosis does not change the skin or shape of the breast. It also does not affect lymph nodes, which are usually not enlarged and appear to function normally.  

woman speaking to her doctor
Terry Vine/Blend Images/Getty Images


Researchers do not know what exactly causes adenosis. However, in 2009, researchers speculated that adenosis lumps may be caused by normal hormonal influences and fluctuations, as well as certain gene mutations. More research is needed.

Risk factors for adenosis are not understood either. Risk factors for benign breast conditions in general include:

  • Being female
  • Being overweight
  • Alcohol consumption
  • Starting your menstrual cycle prior to age 12
  • Use of postmenopausal hormone therapy
  • Use of birth control pills
  • Having your first child after age 35 or never having a child
  • Not breastfeeding if you have had a child
  • Physical inactivity

While these increase your chance of developing adenosis or another benign breast condition, they do not guarantee that you will. Likewise, you may be diagnosed even if you don't have any (or many) of these risk factors.


Given that adenosis can feel similar to other lumps, detecting the condition with a physical exam is usually not enough to confirm a diagnosis—even if the lump is large.

If your healthcare provider is concerned about the possibility of breast cancer or another breast problem, they will ask for imaging tests, including a mammogram and ultrasound. Breast adenosis can show up on a mammogram, but because it can be mistaken as calcifications, it cannot be distinguished from cancer with this test alone.

In order to determine the cause of the abnormal area seen on the mammogram, a biopsy needs to be performed. During a biopsy, a piece of tissue is removed from the suspicious area and examined for disease. There are three different types of biopsies that can be done: a core biopsy, stereotactic core biopsy, and a vacuum assisted biopsy.

Core Biopsy

During a core biopsy, the skin in the area of the biopsy is numbed with a local anesthetic. A core needle is then used to take a sample of tissue. A core needle is a needle with a larger hole to allow for a larger sample of tissue to be removed. This is often done with the assistance of ultrasound to locate the abnormal tissue.

Stereotactic Core Biopsy

In a stereotactic core biopsy, the same type of needle is used as in a standard core biopsy. The difference is that in a stereotactic biopsy, the breast tissue is held in place with plates as during a mammogram. X-ray images are taken of the breast to help determine the best placement for the needle. Once the needle is placed, additional X-rays may be taken to ensure the needle is in the correct place.

Vacuum-Assisted Biopsy

A vacuum-assisted biopsy uses specialized equipment to help suction out more tissue through the needle than can typically be removed with a core needle. This can be done with the assistance of MRI (magnetic resonance imaging) or ultrasound. This type of biopsy can prevent the need for a surgical biopsy (cutting through the skin to remove abnormal tissue) when larger amounts of tissue must be removed, such as when there is a cluster of abnormal findings on a mammogram.


Since adenosis is not cancer, no treatment is necessary. If the breasts become painful, wearing a bra with good support may help. For some women, decreasing the amount of caffeine consumed can help improve symptoms, as well.

If neither of these strategies eases your breast discomfort, talk to your healthcare provider about additional ways to manage your pain.

If you have sclerosing adenosis, your healthcare provider will likely recommend a schedule for routine screening for breast cancer. The reason is there have been studies suggesting an increased risk of breast cancer in people with sclerosing adenosis.

When to See a Doctor

Anytime there is a new lump found in the breast—or if there are any other new symptoms, such as pain or nipple discharge—you should notify your healthcare team. They may want to evaluate you or order imaging to help determine the cause of your symptoms.


Adenosis of the breast is a noncancerous condition in which the lobules increase in size and contain more glands than they usually do. This can cause lumps to form and the breasts to be painful. Adenosis lumps can be seen on a mammogram and may require a sample of the tissue to be biopsied to make sure it isn't breast cancer. If the lumps are proven to be adenosis, no surgical treatment is needed.

A Word From Verywell

Finding a lump (or any change) in your breast can immediately make your mind jump to breast cancer. Learning more about adenosis and other benign conditions that can mimic breast cancer can help you get a better sense of the possibilities and temper any runaway concerns you may have while you wait to see your healthcare provider.

Frequently Asked Questions

  • Does adenosis affect your risk of breast cancer?

    Having sclerosing adenosis, the type of adenosis that causes scar tissue in the breasts, which causes painful enlargement of the lobules, may increase a woman’s risk of developing breast cancer in the future. However, there have been conflicting studies.

  • What does breast adenosis feel like?

    Breast adenosis may feel like firm lumps in the breast. They may also cause some pain or discomfort in the breasts.

  • Should adenosis be removed?

    It is not necessary for adenosis of the breast to be removed, as it is not cancer.

9 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. Visscher DW, Nassar A, Degnim AC, et al. Sclerosing adenosis and risk of breast cancer. Breast Cancer Res Treat. 2014;144(1):205-12. doi:10.1007/s10549-014-2862-5

  3. American Academy of Family Physicians. Benign Breast Conditions.

  4. Worsham MJ, Raju U, Lu M, et al. Risk factors for breast cancer from benign breast disease in a diverse population. Breast Cancer Res Treat. 2009;118(1):1-7. doi:10.1007/s10549-008-0198-8

  5. American Cancer Society. Breast biopsy.

  6. University of California San Francisco. Biopsy for breast cancer diagnosis: Sterotactic core biopsy.

  7. Park H-L, Hong J. Vacuum-assisted breast biopsy for breast cancerGland Surg. 2014;3(2):120-127.

  8. Visscher DW, Nassar A, Degnim AC, et al. Sclerosing adenosis and risk of breast cancerBreast Cancer Res Treat. 2014;144(1):205-212.

  9. National Cancer Institute. Breast changes and conditions.

By Julie Scott, MSN, ANP-BC, AOCNP
Julie is an Adult Nurse Practitioner with oncology certification and a healthcare freelance writer with an interest in educating patients and the healthcare community.

Originally written by Pam Stephan
Pam Stephan is a breast cancer survivor.
Learn about our editorial process