Symptoms and causes

Fibroadenomas are solid breast lumps that usually are:

  • Round with distinct, smooth borders
  • Easily moved
  • Firm or rubbery
  • Painless

You can have one or many fibroadenomas in one or both breasts.

When to see a doctor

In healthy women, normal breast tissue often feels lumpy. Make an appointment with your doctor if:

  • You detect a new breast lump
  • You notice other changes in your breasts
  • A breast lump you've had checked before has grown or otherwise changed and appears to be separate from the surrounding breast tissue

The cause of fibroadenomas is unknown, but they might be related to reproductive hormones. Fibroadenomas occur more often during your reproductive years, can become bigger during pregnancy or with use of hormone therapy, and might shrink after menopause, when hormone levels decrease.

Types of fibroadenomas

In addition to simple fibroadenomas, there are:

  • Complex fibroadenomas. These can contain changes, such as an overgrowth of cells (hyperplasia) that can grow rapidly. A pathologist makes the diagnosis of a complex fibroadenoma after reviewing the tissue from a biopsy.
  • Juvenile fibroadenomas. This is the most common type of breast lump found in girls and adolescents between the ages of 10 and 18. These fibroadenomas can grow large, but most shrink over time, and some disappear.
  • Giant fibroadenomas. These can grow to larger than 2 inches (5 centimeters). They might need to be removed because they can press on or replace other breast tissue.
  • Phyllodes tumor. Although usually benign, some phyllodes tumors can become cancerous (malignant). Doctors usually recommend that these be removed.

Most fibroadenomas don't affect your risk of breast cancer. However, your breast cancer risk might increase slightly if you have a complex fibroadenoma or a phyllodes tumor.

May 18, 2017
References
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  3. Understanding breast changes: A health guide for women. National Cancer Institute. https://www.cancer.gov/types/breast/understanding-breast-changes. Accessed Jan. 30, 2017.
  4. Facts for life: Benign breast conditions. Susan G. Komen. http://ww5.komen.org/BreastCancer/BenignConditions.html. Accessed Jan. 30, 2017.
  5. Ultrasound — breast. RadiologyInfo.org. http://www.radiologyinfo.org/en/info.cfm?pg=breastus. Accessed Jan. 31, 2017.
  6. Cerrato FE, et al. Intermediate and long-term outcomes of giant fibroadenoma excision in adolescent and young adult patients. Breast J. 2015;21:254.
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