Fibroadenomas are not cancerous. They range in size from smaller than a marble to as large as a golf ball. Most appear suddenly and stay the same size. Some shrink or continue to grow. They are affected by hormones and often change size over the menstrual cycle or in pregnancy.

Fibroadenomas are usually rubbery and firm, but they can be difficult to feel properly. If you push on the lump, you will probably find that it moves away from beneath your fingers. This is why some people call a fibroadenoma a ‘breast mouse’. Fibroadenomas do not move far within the breast.

Usually, fibroadenomas are not painful. However, they can be uncomfortable or very sensitive to touch. Often women find that their fibroadenoma gets tender in the days before their period. Pushing or prodding at the lump can also make it tender.

Researchers do not know what causes fibroadenomas. We do know that they are quite common, especially in women aged between 15 and 25. Up to one in six (15 per cent) of women have a fibroadenoma at some time in their life. Sometimes a fibroadenoma can be difficult to distinguish from cancer; therefore further testing may be required.


To diagnose a breast lump as a fibroadenoma, a breast specialist will take into account:

  • any need for further testing to confirm the diagnosis, such as, taking some cells from the lump for testing (core biopsy), needle cytology, or surgical removal 
  • the results of a physical examination and ultrasound or mammogram
  • the history, shape and size of the lump
  • a woman's age
  • whether there is a history of breast or ovarian cancer in the family 
  • if the lump is growing over time.

Deciding what to do about a fibroadenoma

Most fibroadenomas are left alone and not treated. Many women and their specialists decide that there is no need to remove the lump. It is safe to leave fibroadenomas where they are.

While fibroadenomas are not cancerous, it is sometimes difficult for clinicians and women to feel completely confident that a lump is not cancerous. Some of these lumps need to be removed or have a biopsy to stop this concern.

Sometimes a woman asks to have a fibroadenoma removed because it is very uncomfortable or painful. However, the scar resulting from surgery might also be uncomfortable or painful, so this decision needs to be considered very carefully.

If the fibroadenoma is continuing to grow, sometimes a specialist will suggest removing it before it gets larger, simply to lessen the amount of scarring.

Surgical removal of a fibroadenoma

The extent of the operation to remove a fibroadenoma depends on its size. Mostly the operation is performed with a general anaesthetic. Usually women go home the same day. There will be a scar where the fibroadenoma has been removed.

Fibroadenomas and you

Your fibroadenoma does not put you at any increased risk of breast cancer. You should follow the recommendations for screening for breast cancer for women of your age and family history.

All women need to be alert to any changes in their breasts that are not normal for them. If you have any change in your breast that is different to your normal hormonal changes, you should have it checked by your General Practitioner (GP).

For most women, having an unusual breast change is upsetting. It can bring up many different feelings and worries. It’s understandable to fear cancer. It’s also common to find tests stressful and invasive.

Most of the time women feel relieved to know that their breast change is due to a common condition that is not harmful or dangerous. Sometimes, however, they keep worrying about getting cancer. Some women also find that their breast change affects how they feel about themselves, their sexuality or relationships.

If a fibroadenoma is having a negative impact on your life, it might help to share your feelings with supportive family members or friends. You could also get information or advice from your GP or a Women’s Health Nurse at your local community health centre. 

If your fibroadenoma is painful, talk to your specialist or GP or see our information sheet on Breast Soreness.

You and your General Practitioner (GP)

If you have recently seen a specialist at a Breast Clinic, it is a good idea to visit your GP afterwards. That way, you can make sure you fully understand any information, tests or diagnosis that the specialist gave you.

It’s also a good chance to talk about what you are thinking and feeling about your breast change or diagnosis.

Your GP can also help you if you would like a second opinion about your breast change.

If you don’t have a regular GP, ask friends, family or your local community health centre for some suggestions. It’s good to have a regular GP who you know and trust.


The Women’s does not accept any liability to any person for the information or advice (or use of such information or advice) which is provided on the Website or incorporated into it by reference. The Women’s provide this information on the understanding that all persons accessing it take responsibility for assessing its relevance and accuracy. Women are encouraged to discuss their health needs with a health practitioner. If you have concerns about your health, you should seek advice from your health care provider or if you require urgent care you should go to the nearest Emergency Dept.