Giant adenofibroma of the breast is a rare, benign, fibroepithelial tumor which usually manifests as a unilateral, painless, firm, mobile, slow-growing mass in the breast that measures more than 5 cm. It can be associated with significant asymmetry and/or deformity of the breast and hormonal changes (e.g. puberty, pregnancy, oral contraceptives) can lead to its marked enlargement.