A fibroadenoma is a painless, unilateral, benign (non-cancerous) breast tumor that is a solid, not fluid-filled, lump. It occurs most commonly in women between the age of 14 to 35 years but can be found at any age. Fibroadenomas shrink after menopause, and therefore, are less common in post-menopausal women. Fibroadenomas are often referred to as a breast mouse due to their high mobility. Fibroadenomas are a marble-like mass comprising both epithelial and stromal tissues located under the skin of the breast. These firm, rubbery masses with regular borders are often variable in size.
Rapidly growing hyperplastic cells; the pathologist can establish diagnosis after carefully reviewing the biopsy of breast tissue
This fibroadenoma is commonly found in patients age 10 to 18 years. These fibroadenomas have a faster growth rate and eventually shrink or disappear.
This non-cancerous lesion is slightly larger than other types. It commonly needs excision because it compresses or replaces normal breast tissue.
A stromal tumor of the breast that can be either benign or malignant. It is not a fibroadenoma, therefore; it needs to be watched closely. Most doctors recommend removing it.
Causes of fibroadenoma are debatable, but professionals believe that the lesion has a hormonal etiology related to the increased sensitivity of breast tissue to the female reproductive hormone estrogen. Fibroadenoma usually grows during pregnancy and tends to shrink during menopause. This supports the hormonal etiologic theory. Females who take oral contraceptives before 20 years of age tend to suffer from fibroadenoma at higher rates than the general population.
Fibroadenoma tends to occur in early age. It is most commonly found in adolescents and less commonly found in postmenopausal women. The incidence of fibroadenoma decreases with increasing age and generally found before 30 years of age in females in the general population. It is estimated that 10% of the world's female population suffers from fibroadenoma once in a lifetime.
Fibroadenoma arises from stromal and epithelial connective tissue cells that are functionally and mechanically important in the breast. These tissues contain receptors for both estrogen and progesterone. For this reason, fibroadenomas tend to proliferate during pregnancy because of excessive production of female reproductive hormones. Hormone sensitivity causes excessive proliferation of breast connective tissues.
Mediator complex subunit 12 (MED12) gene is also important in the pathophysiology of fibroadenomas.
The histological diagnostic features of fibroadenoma can be described as sheets of uniformly distributed epithelial cells that are typically arranged in a honeycomb pattern. There is a presence of foam cells and apocrine cells and an absence of excessive mitotic activity or anaplasia. Calcification may also be present. Juvenile fibroadenoma has increased in stromal cellularity. The stroma is hypovascular as compared to the malignant neoplasms. The basement membrane also remains intact in fibroadenoma which reflects its benign feature.Microscopic Features
Contains both stromal and epithelial tissues that are arranged in 2 patterns:
Unique Histological Features of Various Fibroadenomas
Age is the most important factor in the incidence of fibroadenoma. Therefore, when obtaining a medical history, age is the most important factor which should be considered.
A family history of breast cancer is also significant. Female patients who have first-degree relatives with breast cancer should be monitored and observed more carefully for malignant features than patients without this family history.
Fibroadenoma most commonly occurs in the upper outer quadrant of the breast. On physical examination, it has the following features:
After a thorough history and physical examination, the following imaging modalities are used for the diagnosis of fibroadenomas.
A mammogram uses x-rays to evaluate the suspicious masses in women above 35 years of age. Fibroadenoma on a mammogram appears as a distinct area from other breast tissue, with smooth round edges. See figure 1.
Mammographic features of fibroadenomas are variable from a well-circumscribed discrete oval mass hypodense or isodense of breast glandular tissue to a mass with macro lobulation or partially obscured margins. Involuting fibroadenomas in older, typically postmenopausal patients may contain calcification, often producing the classic, coarse popcorn calcification appearance.
Ultrasound (US) uses sound waves to detect the features of fibroadenomas in women younger than 35 years of age. US easily differentiates solid from the cystic masses. On US, a fibroadenoma is typically seen as a well-circumscribed, round to ovoid, or macrolobulated mass with generally uniform hypoechogenicity.
If necessary, a minimally invasive biopsy may be performed via a core needle biopsy
In the majority of cases, fibroadenomas need no treatment. They shrink and disappear over time, but if their size is large and they are compressing other breast tissues, they should be removed.
Many females decide against the surgery because the lesions are harmless and involve no long-term risk of malignancy. Surgery also distorts the shape of a breast.
Doctors might decide to remove fibroadenoma if it is massive and continues to increase in size.
Indications for surgical intervention include rapid growth, size greater than 2 cm, and patient request.
There are 2 surgical procedures used to remove a fibroadenoma:
A fibroadenoma can be confused with:
Prognosis of fibroadenoma is good because it is a benign mass which shrinks in size over time in the majority of cases.
Breast cancer risk may slightly increase in patients with a complex fibroadenoma. This type of lesion may contain calcified breast tissue.
An interprofessional approach to fibroadenoma is recommended.
The majority of breast lesions in young women are identified on an incidental breast exam either by the patient or the healthcare provider. Even though fibroadenomas are benign lesions, sometimes there may be a need to confirm the histology. Healthcare workers including nurse practitioners should never assume that all firm, rubbery lesions are benign. If ever in doubt, get a radiologist or surgeon to perform a biopsy. Missing a malignant breast lesion in a young female can lead to litigation.
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