A fibroadenoma is a common benign tumor of the breast found in an estimated 10 percent of all women. Approximately 10 to 15 percent of affected individuals have multiple fibroadenomas. The solid masses are most prevalent in young women between the ages of 15 and 30 and tend to grow larger in women that are pregnant.

Some researchers suggest a link between the hormone estrogen and fibroadenoma development based upon this information as well as the fact that the tumors occur in postmenopausal women taking estrogen, but not in those that do not receive such hormone replacement therapy. It is not yet fully understood, however, why some women develop fibroadenomas and others do not or why some studies indicate that the tumors are twice as common among black women as they are among white women.

Fibroadenomas, which are generally firm, smooth, and round, can be readily moved under the skin and are often described as feeling similar to marbles. Typically the masses measure from 1 to 3 centimeters in size, but occasionally they may grow much larger, in which case they are termed giant fibroadenomas. The tumors are usually painless and present no symptoms, typically being discovered by young women only due to self-examination.

Since they are usually benign and typically stop growing after only reaching a few centimeters in diameter, fibroadenomas are often left alone after they are diagnosed. Even without treatment, approximately 10 percent of fibroadenomas fully recede each year. In cases where pain or tenderness occurs due to the tumors or the tumors grow unusually large, however, excision may be recommended. The tumors recur in about 20 percent of patients.

Though fibroadenomas are benign, many other growths that may develop in breast tissue are not. Consequently, it is very important that any lump detected in the breast is brought to the attention of a medical professional. Several different diagnostic tests aid doctors in providing an accurate diagnosis. The most common investigative techniques used for individuals with a suspected fibroadenoma include mammograms, ultrasound scans, aspirated biopsies, and core biopsies.

Fibroadenoma at 10x Magnification - Fibroadenomas, which arise from the intralobular stroma, are solid and consist of a combination of glandular and fibrous tissues.

Fibroadenoma at 20x Magnification - In older women, fibroadenomas are often less palpable than they are in younger women and are often first discovered during a routine mammogram.

Fibroadenoma at 10x Magnification - Many fibroadenomas that are removed are treated in an outpatient venue under local or general anesthesia, though some surgeries require an overnight stay in a hospital.