A fibroadenoma is a benign, or noncancerous, growth within the breast. Fibroadenomas are among the most common of all breast tumors. They occur most frequently in women younger than age 30 but can arise at any age.

The breast is comprised of 2 main types of tissue: glandular and supportive. The glandular portion includes the lobules, which produce milk in women who are breastfeeding, and the ducts, which carry milk from the lobules to the nipple. The supportive portion includes the fibrous connective tissue and fatty tissue that determine the size and shape of the breast.

Fibroadenomas are benign, harmless tumors comprised of both glandular and supportive breast tissue. Their actual cause is not known, though their development is thought to be related to developmental hormones: fibroadenomas occur in greater frequency during the reproductive years, tend to increase in size during pregnancy or hormone therapy, and typically shrink after menopause, when hormone stimulation decreases.  Fibroadenomas are usually single, painless, round lumps that feel firm or rubbery, have distinct borders, and are easily movable under the skin. About 10-15% of women with fibroadenomas have more than one lump, which may affect one or both breasts.

Fibroadenomas are classified as simple or complex and they can range in size from microscopically small to several inches in diameter, with most being about the size of a marble. The vast majority are simple; these fibroadenomas have a consistent composition when examined under a microscope and do not increase the risk of breast cancer development. Complex fibroadenomas contain additional components, such as calcifications (tiny mineral deposits), when viewed under a microscope. In general, about half of all fibroadenomas will disappear within 5 years; the other half will either get larger or remain the same in size.

Treatment Options

Treatment for fibroadenomas may not be necessary unless they are large, painful or cosmetically undesirable, in which cases they can be removed. Fibroadenomas do not grow back after they are removed; however, some women do develop new fibroadenomas after having previous lumps removed.


The following treatment options are available:

  • Watchful Waiting – Fibroadenomas are usually left in place and monitored for growth. Women will multiple, non-growing lumps may choose this tactic because removal would likely affect the shape of the breast. If the lump is left in place, women may need to be followed regularly by their doctors through clinical breast exams and imaging tests such as mammograms (breast X-rays) or ultrasound. If the lump changes, grows, or doesn’t go away, it may need to be removed at a later time.

  • Removal – Cutting out fibroadenomas with a scalpel, or traditional excision, is a treatment method used in some cases. A small slit is made in the skin and an ultrasound probe is used to guide a vacuum to the lump, which is then extracted in sections. This procedure is usually done in the Operating Room.