Unilateral<unk>  is usually caused by Poland's syndrome, which is characterized by one side absence of breast. The absence or dysfunction of pectoralis muscle and ribs are common case. It can also be part of other syndromes as described in the previous contents. Other causes may include intra-uterine exposure to teratogenic drugs such as dehydroipiandrosterone and methiamozole/carbimazole treatment during first trimester. For bilateral<unk> , the cause has not been well understood so far. It may be related to gene mutation since often patients with bilateral<unk>  are diagnosed as autosomal dominant and recessive inheritance. Decreasing blood flow in the subclavian artery may also be a cause of<unk> .<unk>  can also be caused by injuries. These injuries may happen when patients receive surgery, such as thoracotomy, chest tube placement, or when they are treated by radiotherapy. Improper biopsy or severe burns of breast tissue may also result in<unk> .
Amastia
Hamartia 
Macrodontia 
Macrotia
Acrania
Spotted lunulae
Cystic eyeball
Auricular hypertrichosis