What is Fibroadenoma?

A fibroadenoma is a smooth, discrete breast lump consisting of fibrous and adenomatous (glandular) tissue. It is firm and mobile that it appears to shift position and is commonly referred to as a ‘breast mice’.

Fibroadenoma is the most common benign tumour of the breast and the most common breast tumour in women under age 30.

Fibroadenomas are usually found as single lump, but about 10 – 15% of women have several lumps that may affect both breasts.

What Causes Fibroadenomas?

The exact cause of fibroadenomas is unknown.

They seem to be influenced by estrogen, because they appear most often in premenopausal or pregnant women, or in women who are postmenopausal and on hormone replacement therapy (HRT).

Most fibroadenomas come and go during your menstrual cycle, when your hormone levels are changing.

When Do Fibroadenomas Appear?

These are most common in young women aged 15 to 30 years and in pregnant women.

Fibroadenomas occur in 10 percent of all women, but in 20 percent of African-American women.

They are much less common in postmenopausal women, unless the women is on estrogen therapy.

About 10 percent of all fibroadenomas will disappear over time and 20 percent of them will recur.

If they don’t disappear, they usually stop growing when they reach two or three centimetre.


Can You Feel a Fibroadenoma?

While doing your regular breast self-examination, you may feel a breast fibroadenoma. These feel firm, rounded, smooth, rubbery and are movable. They are mobile because they tend to run away from your fingers.

A fibroadenoma may feel tender, especially right before your period, when it may swell due to hormonal changes.

What Sizes Are Fibroadenomas?

Fibroadenomas range in size from one to five centimetre. Giant fibroadenomas can be the size of a small lemon, about 15 centimetre.

Examination and test:

After a careful physical examination, one or both of the following tests are usually done to determine further information:

  • Breast ultrasound
  • Mammogram for women above 35 years old who is at risk of breast cancer

A biopsy is needed to get a definite diagnosis. Fine needle aspiration biopsy is most often performed.

Note: Women in their teens or early 20s may not need a biopsy if the lump goes away on its own. (may happen if size of the breast lump less than 1 cm)


If the lump is left in place and carefully watched, it may need to be removed at a later time if it changes, grows, or doesn’t go away.
They rarely changes to cancer.


Treatment or Removal of Fibroadenomas:

Since fibroadenomas are benign, treatment will vary depending on the diagnosis.

If it is small, painless, remains the same size, and a biopsy shows no problems, you would not need further treatment, but may have follow-up ultrasounds (normally the size is less than 1cm).

However, if it is large (more than 2 cm), painful, growing, or a biopsy results in atypical (very active) cells, you can have it surgically removed with a lumpectomy.


Why examine your breasts?

Regular breast self examination (BSE) helps you to become familiar with the usual feel of your breasts.

You will detect any lumps in the breast at an early stage of their development.

Although only 1 in 10 breast lumps is cancer, 1 in 15 women is at risk of breast cancer in their life time.

Most breast cancers are found (as a lump) by the woman, not by the doctor.

Early detection of a lump, if it is a breast cancer may mean a better chance of a cure (the smaller lump the better chance to cure).

When should it be done?

Breast examination should be done once a month a few days after the end of your period (day 10 to 15 counting from day of menses). For post menopausal women to do it at same date every month.

What should you do if you find a lump or thickening?

If you find a lump, dimpling of the skin or a discharge from nipple, make sure you see your doctor as soon as possible.

Please do not be afraid or put it off. Most changes are not cancer.


What is Clinical breast examination?

Clinical breast examination is routinely done by trained health care provider to clinically palpate your breast to find any abnormality which can be done yearly at the nearest clinics.

What is the prognosis?

The prognosis is excellent, although patients with fibroadenoma have a slightly higher risk of breast cancer later in life. Lumps that are not removed should be checked regularly by physical exams and imaging tests, following the doctor’s recommendations.


  1. John Murtagh’s Patient Education, Fifth edition
  2. Iglehart JK, Smith BL. Diseases of the breast. In: Townsend CM Jr, Beauchamp RD, Evers BM, Mattox KL, eds. Sabiston Textbook of Surgery. 18th ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 34.
Last Reviewed : 28 August 2020
Writer : Dr. Norizzati Bukhary bt. Ismail Bukhary
Accreditor : Dr. Rohana bte. Ahmad
Reviewer : Dr. Nazhatussima bt. Suhaili