Definition

A type of benign (not cancer) tumor that usually forms in the breast and is made up of fibrous (connective) and glandular tissue. In complex fibroadenomas, other abnormal tissue changes are also present. These changes may include cysts, calcifications, scar-like tissue, and hyperplasia (an increase in the number of cells in the breast ducts or lobes). Complex fibroadenomas are more common in older women and may slightly increase the risk of breast cancer.