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Fibroadenomas of the Breast
Fibroadenomas are common, benign (noncancerous) breast tumors. They are made up of both glandular tissue and stromal, or connective, tissue.
Fibroadenomas are most common in women in their 20s and 30s, but they can be found in women of any age.
Fibroadenoma symptoms and signs
Fibroadenomas can often feel like a marble within the breast. They tend to be round or oval and have clear borders. You can move them under the skin, and they’re usually firm or rubbery, but not painful.
Some fibroadenomas of the breast are too small to be felt, but some can be up to several inches across. A woman can have one or many fibroadenomas.
Some fibroadenomas aren’t felt but are found by an imaging test, such as a mammogram or ultrasound.
Diagnosis of fibroadenomas
A breast biopsy is the best way to tell if a breast mass is a fibroadenoma or some other condition.
There are 2 main types of fibroadenomas:
- Simple fibroadenomas are the most common type. They look the same all over when seen under a microscope.
- Complex fibroadenomas have other types of changes known as proliferative changes. Complex fibroadenomas tend to be bigger and to occur in older people.
What causes fibroadenomas?
The cause of fibroadenomas is not known, but they are likely related to hormone levels. They are most common during a woman’s reproductive years. They tend to get larger during pregnancy and to shrink after menopause.
How do fibroadenomas affect breast cancer risk?
Simple fibroadenomas do not seem to increase breast cancer risk. Complex fibroadenomas may increase the risk slightly more than simple fibroadenomas.
In general, breast cancer screening recommendations aren’t different for women diagnosed with a fibroadenoma.
Do fibroadenomas need to be treated?
Not all fibroadenomas need treatment. But doctors might recommend treating them if they:
- Are large or changing the shape of the breast
- Are growing
- Are causing bothersome symptoms
- Don’t look like a typical fibroadenoma on an imaging test such as a mammogram
How are fibroadenomas treated?
If the diagnosis of fibroadenoma has been confirmed on a biopsy and it needs to be treated, surgery is usually the main option, especially if it is large.
Another option for some women might be cryoablation, especially if it is smaller. In this procedure, a thin needle is inserted into the fibroadenoma. The tip of the needle releases extreme cold that freezes and destroys the cells.
Some fibroadenomas stop growing or even shrink on their own without any treatment. These may only need to be monitored by the health care team to make sure they do not grow. This approach is useful for women with many fibroadenomas that aren’t growing. In such cases, removing them might mean removing a lot of nearby normal breast tissue, causing scarring and changes in the shape and texture of the breast.
It’s important that women with fibroadenomas have regular breast exams or imaging tests to make sure the fibroadenomas do not grow.
Sometimes one or more new fibroadenomas can appear after one is removed. This usually means that another fibroadenoma has formed. It does not mean that the old one has come back.
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- References
Developed by the American Cancer Society medical and editorial content team with medical review and contribution by the American Society of Clinical Oncology (ASCO).
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Last Revised: May 26, 2026
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