IS Case 198: Fibroadenoma

Lisa Siripun, MD

Imaging Sciences URMC 2008
Publication Date: 2009-05-22


A 42-year-old female was found to have a breast mass on chest CT.




Fibroadenomas are benign tumors composed of stromal and epithelial elements. These tumors are commonly seen in young women. Hormonally mediated changes in size and associated tenderness are seen with fibroadenomas. Fibroadenomas are benign lesions and are not considered to have malignant potential. However, because they contain epithelium, a risk of neoplasia exists, as in other locations in the breast. The risk of a breast carcinoma occurring within a fibroadenoma is about 3%. They do not usually develop in post-menopausal woman unless the patient is on hormone therapy. Approximately 10% of fibroadenomas disappear spontaneously each year, and most stop growing after they reach 2-3 cm.

Patient's age determines the preferred imaging method. In general, ultrasonography (US) is preferred if a palpable mass is found, if a patient is younger than 30 years, or if the patient is pregnant. Mammography and US are both useful if the patient has a palpable mass, is older than 30 years, and is not pregnant.

Mammographically, they are variable in appearance but frequently are well-circumscribed oval masses. Occasionally, fibroadenomas contain coarse calcifications, which suggest infarction and involution. Calcifications may be useful in diagnosing the mass, but occasionally, they may mimic malignant microcalcifications. Although fibroadenomas often have coarse calcifications, cystosarcomas rarely have calcifications. Mammography cannot be used to distinguish whether a mass is a fibroadenoma, a cyst, or a carcinoma with certainty because of some overlap in the findings. All of the entities may appear as smooth masses.

On ultrasound, they are often well-circumscribed, homogeneous, hypoechoic masses with a thin echogenic rim and a wider than tall orientation. We may or may not see posterior acoustic enhancement. Macrolobulation of contours may be present. Fibroadenomas often demonstrate a typical appearance and may be distinguished clearly from cysts and carcinomas; however, fibrocystic disease with complicated hypoechoic cysts and, rarely, smooth carcinomas may mimic fibroadenoma. Atypical fibroadenomas, which are inhomogeneous or irregular in shape, may simulate carcinoma.


  1. Roubidoux MA. Breast, fibroadenoma. eMedicine, Feb 16, 2007.
  2. Cardenosa G. Breast Imaging Companion. 3rd ed., Lippincott, Williams and Wilkins, 2007:327-337.

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