Fibroadenomas occur in about 10 percent of women seen in breast clinics, but account for about one half of all breast biopsies. These benign lesions occur more often in women of higher socioeconomic status and in women who are darker-skinned. The risk of developing fibroadenomas is not related to age of menarche or menopause, or to use of hormonal therapy. Conversely, higher body mass index, greater number of full-term pregnancies, higher intake of vitamin C and cigarette smoking are associated with a decreased risk of these lesions. Greenberg and associates present a literature-based approach to fibroadenomas and propose practical algorithms for their management.

Breast fibroadenomas are usually detected incidentally during clinical or self-examinations and are most often located in the upper outer quadrants. The majority are smooth, mobile, nontender and rubbery. Some women have multiple fibroadenomas; these patients usually have a family history of fibroadenomas. Rarely, adolescent girls may develop lesions larger than 5 cm, called juvenile (or giant) fibroadenomas. Although much larger than typical fibroadenomas, these giant fibroadenomas are also benign and do not become malignant. Sonography, often used to diagnose fibroadenomas, reveals a round or oval solid mass with a smooth contour and weak internal echoes. Sonography is able to distinguish between solid and cystic lesions but cannot reliably distinguish fibroadenoma from breast cancer. In one study, about 18 percent of fibroadenomas could not be seen in an ultrasound study of the breast. In a mammogram, a fibroadenoma appears as a soft, homogenous, circumscribed nodule, sometimes with inner coarse calcifications. Fine-needle aspiration reveals characteristic cytologic features and can be used to improve clinical diagnosis of fibroadenoma. Fine-needle aspiration rarely gives a false-positive result, even though it may confuse fibroadenomas with other benign lesions.

Depending on the patient's age, family history and history of previous biopsies, conservative treatment of fibroadenomas may or may not be warranted. A woman under 25 years of age with fibroadenomas is unlikely to have a “missed” malignancy if she has had a clinical examination, negative sonography and negative fine-needle aspiration. (The risk of a missed malignancy in this situation has been estimated to be one in 229 cases to one in 700 cases.) It is not until age 35 that the risk increases somewhat. Multiple fibroadenomas should be excised, with care taken to avoid scarring or ductal damage, which may occur when one incision is used. Giant fibroadenomas generally shrink after hormonal balance is achieved (e.g., after cessation of lactation), so conservative management is preferred, with excision warranted after the lesions become smaller.

The authors conclude that, in women younger than 35 years, conservative management of fibroadenomas is recommended, with a follow-up every six to 12 months until complete regression. Fibroadenomas that don't regress or that remain unchanged by age 35 should be excised. Women older than 35 years should have mammograms in addition to the above-mentioned diagnostic modalities, with follow-up after six to 12 months. If the fibroadenoma has not resolved after 12 months, excision is recommended. Even when conservative management is reasonable, patients often prefer excisional biopsy of persistent fibroadenomas. The authors advise excisional biopsy of any mass for which a diagnosis of fibroadenoma is not clear-cut; however, if, after a clinical examination, ultrasound examination and fine-needle aspiration, a diagnosis of multiple fibroadenomas can be confidently made, conservative treatment is warranted.

editor's note: When mammography is going to be used to assist in the diagnosis of fibroadenomas, it should be performed before fine-needle aspiration, so that subsequent hematoma formation does not distort the mammographic picture. It should also be emphasized that when the nature of a lesion is not definite after ultrasonography, mammography and fine-needle aspiration, the lesion should be excised.—g.b.h.