Fibroadenomas of the Breast

A tumor in the breast represents the most common complaint for which women consult a physician, referring to their change as a mass or a thickening. Approximately 70% of all breast tumors are benign, while fibroadenomas are considered the second most common benign breast lesion with an incidence of 18-20% (following omnipresent fibrocystic changes in the breast).

Fibroadenoma in the breast - Image Copyright: Timonina / Shutterstock
Fibroadenoma in the breast - Image Copyright: Timonina / Shutterstock

Fibroadenomas are important as they comprise almost 50% of all breast biopsies (this rate climbs to 75% for biopsies in women younger than 20 years). The expert consensus of opinion is that women with these changes are not at higher risk of developing breast cancer.

Risk and Protective Factors

Fibroadenomas are usually seen among women who belong to higher socioeconomic classes, but also in dark-skinned individuals. Moreover, the number of full-term pregnancies and body mass index (BMI) were found to negatively correlate with the risk of fibroadenoma development.

On the other hand, the age of menarche and menopause, as well as the usage of hormonal therapy (including oral contraceptive tablets) were shown not to modify the risk of these lesions. Cigarette smoking and vitamin C supplementation are linked to reduced risk of fibroadenomas.

Pathology of Fibroadenomas

Fibroadenomas are considered hyperplastic lesions that are associated with anomalies in the normal maturation of the breasts, rather than genuine neoplasms. This theory is supported by molecular analysis which has shown that both the epithelial and the stromal cells are polyclonal in these lesions.

There are two main histopathological variants of fibroadenomas: juvenile or cellular fibroadenoma that grows rapidly and is associated with projecting veins and skin ulcerations, and giant fibroadenoma that displays a substantial degree of stromal cellularity and is usually larger than five centimeters in diameter.

Estrogen and progesterone (two primary ovarian hormones) and lactation during pregnancy can successfully stimulate fibroadenomas, whereas in menopause they undergo atrophic remodeling. Some of them bear receptors on their surface and respond to human epidermal growth factor (EGH) and growth hormone.

They are rarely seen in older patients, where they may go through involutional change – either due to increased stromal growth or because of an unrecognized infarction with necrosis. The end-result is calcified or hyalinized fibroadenomas.

In those rare occasions of malignant transformation of fibroadenomas, 50% of such tumors show histopathological characteristics of lobular carcinoma in situ, 20% of infiltrating lobular carcinoma, whereas 20% are ductal carcinoma in situ. The remaining 10% of such malignancies are infiltrating ductal carcinoma.

Clinical Presentation

Fibroadenomas clinically present as solid breast lumps that are usually round and firm with distinct borders, non-tender and easily movable. They are usually between 2 and 3 cm in size, albeit they can be smaller than 1 cm or larger than 10 cm.

Furthermore, these lesions can be solitary or multiple. Between 10 and 16% of patients have multiple fibroadenomas (up to four of them in a single breast), which may be present from the start or discovered over a period of years. Although genetics usually does not play a significant role in fibroadenoma development, most of the patients with multiple lesions exhibit a strong family history.

Further Reading

Last Updated: Feb 26, 2019

Dr. Tomislav Meštrović

Written by

Dr. Tomislav Meštrović

Dr. Tomislav Meštrović is a medical doctor (MD) with a Ph.D. in biomedical and health sciences, specialist in the field of clinical microbiology, and an Assistant Professor at Croatia's youngest university - University North. In addition to his interest in clinical, research and lecturing activities, his immense passion for medical writing and scientific communication goes back to his student days. He enjoys contributing back to the community. In his spare time, Tomislav is a movie buff and an avid traveler.


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  1. Jess Wynn-Grant Jess Wynn-Grant United States says:

    Hello, this article needs to be reviewed and edited. "Fibroadenomas are usually seen among women who belong to higher socioeconomic classes, but also in dark-skinned individuals." What do you mean in this sentence? Are you saying that Fibroadenomas are more common in white women than in women of color (also what about between different ethnicities)? OR are you saying that Fibroadenomas are found more frequently in women who are a higher socioeconomic class (probably because of access to resources, screening etc.) and because of systemic racism within the health field.

The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of News-Medical.Net.
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