Fibroadenoma Fibroadenomas are the most common benign tumors of the breast. In one series, they accounted for 50% of all breast biopsies (141). They usually occur in young women (age 20 to 35 years) and may occur in teenagers (142). In women younger than 25 years, fibroadenomas are more common than cysts. They rarely occur after menopause, although occasionally they are found, often calcified, in postmenopausal women. For this reason, it is postulated that fibroadenomas are responsive to estrogen stimulation. A study reports the de novo occurrence of fibroadenoma in 51 women older than age 35 years who had no evidence of a palpable or mammographic visualized lesion in well-documented prior visits (143). Fibroadenomas may appear as single masses or as multiple lesions.
Clinically, a young woman usually notices a mass while showering or dressing. Most masses are 2 to 3 cm in diameter when detected, but they can become extremely large (i.e., the giant fibroadenoma). On physical examination, they are firm, smooth, and rubbery. They do not elicit an inﬂammatory reaction, are freely mobile, and cause no dimpling of the skin or nipple retraction. They are often bilobed, and a groove can be palpated on examination. On mammographic and ultrasonographic imaging, the typical features are of a well-defined, smooth, solid mass with clearly defined margins and dimensions that are longer than wide and craniocaudad dimensions that are less than the length.
Fibroadenoma is not associated with an increased risk for breast cancer (144). The natural history of fibroadenoma can be regression, growth, or no change in size. Most fibroadenomas are static or cease growth at approximately 2 to 3 cm, about 15% of tumors regress spontaneously, and only 5% to 10% progress (145). Because transformation of a fibroadenoma into cancer is rare and regression is frequent, current management recommendations are conservative unless there is evidence of growth (141). A suspected fibroadenoma should be confirmed by FNAC or CNB and observed for increase in size or excised based on patient preference. Rarely will the fibroadenoma increase to more than 2 to 3 cm in size. Large or growing fibroadenomas must be excised. Complete excision of a fibroadenoma with local anesthesia can be performed to treat the lesion and confirm the absence of malignancy. Less invasive local treatment of a fibroadenoma is advocated by some and can be performed with either ultrasonographically guided percutaneous vacuum-assisted biopsy devices or percutaneous cryoablation (146,147). A young woman with a clinical fibroadenoma can undergo needle cytology and observation of the mass (148). Acceptance of observation varies, and many women choose to have the fibroadenoma excised (149).
On gross examination of an excised mass, the fibroadenoma appears encapsulated and sharply delineated from the surrounding breast parenchyma. Microscopically, there is proliferation of both the epithelial and stromal component. In longstanding lesions and in postmenopausal patients, calcifications may be observed within the stroma.
Multiple Fibroadenomas Multiple fibroadenomas occur in some women and were reported to occur more frequently in premenopausal women undergoing immunosuppression for transplant (150–152). Excision of all lesions through separate incisions could leave significant scarring and deformity. Excision of these mobile lesions through a single periareolar incision was suggested, but this approach can lead to significant ductal disruption (153). Another approach is through an incision in the inframammary crease. Alternatively, these lesions can be treated with observation based on triple-test concordance of results of a classic clinical examination with histologic corroboration with FNAC and ultrasonographic diagnostic criteria consistent with a fibroadenoma (151).