Mondo Description Familial juvenile hypertrophy of the breast is a rare breast malformation disorder characterized by unilateral or bilateral, symmetrical or asymmetrical, uncontrolled, rapid and massive enlargement of the breast(s) in peripubertal females, occurring in various members of a family. Additional associated manifestations may include skin hyperemia, dilated subcutaneous veins, skin necrosis, kyphosis, lordosis and anonychia. Growth and development are otherwise normal.