Mastopoiesis is a congenital malformation of the breasts caused by an abnormal embryonic development. It is rare and is often accompanied by underdevelopment or absence of thoracic tissue. The main treatment is breast reconstruction, which is very rare in males and is hereditary. Breast deficiency is mostly manifested as absence of one breast or both breasts, in which absence of one breast is more common and absence of both breasts is more rare. Some patients may even be accompanied by developmental defects of the shoulder, chest and upper limbs on the same side, such as absence of pectoralis major muscle, sternum, part of ribs, and flatness or even concavity of the corresponding part of the chest wall, and it may be accompanied by developmental defects of the bones and kidneys, and incomplete development of the teeth. Breast deficiency can also be accompanied by skeletal and renal developmental defects, poor dental development, etc.