A juvenile gigantomastia with wet tender ulceration in a 13-year-old premenarchal girl (155 cm, 51 kg) developed in only 6 months. Treatment consisted of a bilateral reduction mammoplasty with free transplantation of the areolae and nipples and the removal of 4.2 kg of breast tissue. Macroscopically the resections consisted of "white and solid" tissue. Histologically a fibrous-cystic mastopathia was confirmed. It is thus suggested that the etiology of this disease might be related to a local hypersensitivity to estrogen. Mediactions (Tamoxifen) are mostly ineffective. The treatment consisted of reduction plasty.