Fibroadenoma at 40x Magnification

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.