What are fibroadenomas?

Risk factors: Fibroadenomas require the presence of estrogen to develop and grow, so they occur between menarche and menopause. Generally, after menopause, an existing fibroadenoma will stop growing and may even disappear. If a woman takes estrogen after menopause, she can develop a fibroadenoma.

Etiology and the disease process: A fibroadenoma arises from a single milk duct in the breast and is made up of both glandular (milk-producing cells) and epithelial cells (skin cells that line the duct). There is no fluid inside a fibroadenoma. It develops from an overgrowth of the affected breast tissue. The cause of the overgrowth of tissue is unknown, although estrogen is required for fibroadenoma development.

Fibroadenomas generally stop growing at 2 to 3 cm, although they occasionally grow larger. They may also enlarge during pregnancy and at times of higher estrogen levels during the menstrual cycle.

Immunosuppressive medications appear to have an effect on the growth and development of fibroadenomas. Studies have demonstrated that 50 percent of women who receive the immunosuppressive drug, cyclosporine, after a kidney transplant will develop one or more fibroadenomas.

Incidence: The fibroadenoma is the most common type of benign breast tumor; in 2014 Chinyama noted that the incidence of fibroadenoma varies with publication. In women over the age of forty, 8 to 10 percent will develop a fibroadenoma at some time during their lives. Roughly one-third of fibroadenomas are complex fibroadenomas.

Symptoms: In women younger than age forty, fibroadenomas usually appear as palpable (can be felt) breast masses. After age forty, they may be discovered as a palpable breast mass, or they may appear on mammography as a breast mass that is not palpable. Fibroadenomas are not painful.

Screening and diagnosis: Screening is not carried out specifically for fibroadenomas, but some are picked up while screening for breast cancer in women over the age of forty. Breast fibroadenomas may be diagnosed by breast self-examination if they are palpable, or by mammography. On a mammogram, a fibroadenoma appears as a dense area in the breast, and in women over age forty, it may have areas of calcification (mineral deposits). Since it is not possible to determine whether a breast density is a fibroadenoma or breast cancer on mammography, subsequently, a breast ultrasound is performed. On an ultrasound, a fibroadenoma looks like a clear area with defined edges, much as a breast cyst does. The only way to determine whether a density is, indeed, a fibroadenoma is to biopsy it. A biopsy may be performed using a fine needle, a core needle, or surgical incision. A pathologist examines the tissue under a microscope and decides whether it is cancer or a fibroadenoma.

A cancer is present inside 3 percent of fibroadenomas. Typically, these fibroadenomas are larger than usual and have irregular margins that are less clearly defined. In 1 percent of cases, what appears to be a fibroadenoma is actually a malignant phyllodes tumor.

Because a fibroadenoma is not cancer, there is no staging for it. If breast cancer is found within a fibroadenoma, it is staged as a breast cancer.

Treatment and therapy: A fibroadenoma may be totally removed at the time of biopsy by surgical excision or core needle biopsy. If it is not removed, it will be monitored annually for growth and changes by mammography, magnetic resonance imaging (MRI), or ultrasound.

Prognosis, prevention, and outcomes: Since fibroadenomas are benign tumors, the prognosis is excellent for women who develop them. There is a slight increase in the risk of subsequently developing breast cancer. Before menopause, there is no way to prevent a fibroadenoma from developing. After menopause, a woman can prevent a fibroadenoma by avoiding any type of systemic estrogen therapy.

Bibliography

Amer. Cancer Soc. "Fibroadenomas." Cancer.org. ACS, 14 Jan. 2014. Web. 23 Oct. 2014.

Amer. Cancer Soc. "Types of Breast Cancer." Cancer.org. ACS, 25 Sept. 2014. Web. 13 Nov. 2014.

Amer. Coll. of Obstetricians and Gynecologists. FAQ026, Gynecologic Problems: Benign Breast Problems and Conditions. N.p.: ACOG, 2012. Digital file.

Chinyama, Catherine N. Benign Breast Disease: Radiology, Pathology, Risk Assessment. 2d ed. New York: Springer, 2014. Print.

Ganschow, Pamela, et al., eds. Breast Health and Common Breast Problems: A Practical Approach. Philadelphia: Amer. Coll. of Physicians, 2004. Print.

Love, Susan, and Karen Lindsey. Dr. Susan Love’s Breast Book. 5th ed. Cambridge: Da Capo, 2013. Digital file.

Mayo Clinic. "Fibroadenoma." Mayo Clinic. Mayo Foundation for Medical Education and Research, 2 May 2014. Web. 23 Oct. 2014.

Tan, P. H., I. O. Ellis. "Myoepithelial and Epithelial-Myoepithelial, Mesenchymal and Fibroepithelial Breast Lesions: Updates from the WHO Classification of Tumours of the Breast 2012." Jour. of Clinical Pathology 66.6 (2013): 465–470. NCBI PubMed.gov. Web. 13 Nov. 2014.

Wechter, Debra G. "Fibroadenoma—Breast." MedlinePlus. US NLM/NIH, 15 Nov. 2013. Web. 23 Oct. 2014.