What is a fibroadenoma?

Breasts are made up of lobules (milk-producing glands) and ducts (tubes that carry milk to the nipple), which are surrounded by glandular, fibrous supporting tissue and fatty tissue. Fibroadenomas develop from a lobule. The glandular tissue and ducts grow over the lobule and form a solid lump.

breast diagram illustration checking

Fibroadenomas are benign (not cancer) and don’t increase the risk of developing breast cancer. They are thought to occur because of an increased sensitivity to the female hormone oestrogen.

A fibroadenoma usually has a smooth rubbery texture and can move easily under the skin. Fibroadenomas are usually painless, but some people may feel some tenderness or even pain.

Fibroadenomas are very common and it is not unusual to have more than one. Often developing during puberty, they are mostly found in young women, but can occur at any age.

Most fibroadenomas are about 1 to 3cm in size and are called simple fibroadenomas. Occasionally, a fibroadenoma can grow to more than 5cm and may be called a giant fibroadenoma. Those found in teenage girls may be called juvenile fibroadenomas.

Most fibroadenomas stay the same size. Some get smaller and some eventually disappear over time. Sometimes fibroadenomas get bigger, particularly in teenage girls and pregnant and breastfeeding women, but often get smaller again.

How are they diagnosed?

Fibroadenomas usually become noticeable as a lump in the breast. When you have a breast examination, your GP (local doctor) will sometimes be able to say whether the lump feels like a fibroadenoma. However they’re likely to refer you to a breast clinic where you’ll be seen by specialist doctors or nurses.

At the breast clinic you’ll undergo various investigations known as ‘triple assessment’ so that a definite diagnosis can be made. This assessment consists of:

Fibroadenomas are often easier to identify in younger women. If you are in your early 20s or younger, your fibroadenoma may be diagnosed by examination and ultrasound only. However, if there is any uncertainty, an FNA or core biopsy can be done.

If you are under 40, you’re more likely to have an ultrasound than a mammogram. Younger women’s breast tissue can be dense which can make the x-ray image less clear so normal changes or benign breast conditions can be harder to identify. However, for some women under 40 mammograms may still be needed to complete the assessment.

Follow-up or treatment

In most cases you won’t need any follow-up or treatment if you have a fibroadenoma. Usually you’ll only be asked to go back to your GP or the breast clinic if it gets bigger or becomes painful.

Sometimes an operation called an excision biopsy is required to remove large fibroadenomas. You can also request to have a fibroadenoma removed. 

You may be offered a vacuum assisted excision biopsy to remove the fibroadenoma. This is a way of removing small fibroadenomas under local anaesthetic, without having surgery. After an injection of local anaesthetic, a small cut is made in the skin. A hollow probe connected to a vacuum device is placed through this. Using ultrasound or mammography as a guide, breast tissue is sucked through the probe by the vacuum into a collecting chamber. The biopsy device is used in this way until all of the fibroadenoma has been removed. This may mean that an operation under a general anaesthetic can be avoided. The tissue removed is sent to the laboratory and examined under a microscope. This procedure can cause some bruising and pain for a few days afterwards.

Removing a fibroadenoma doesn’t usually affect the shape of the breast, but a slight dent may be noticeable.

What this means for you

Having a fibroadenoma does not increase your risk of developing breast cancer. However, it’s still important to be breast aware and go back to your GP if you notice any changes in your breasts, regardless of how soon these occur after your diagnosis of a fibroadenoma.

Last reviewed: March 2014
Next planned review is March 2016

Let us know what you think

Please note that we cannot respond to comments. If you have any questions about breast cancer please contact the Helpline on 0808 800 6000.

Get the latest breast cancer updates


Related Publication