Therefore, when amastia patients receive medical ultrasound examination, asymmetry or disproportioned mammary tissue may be found. Causes
Unilateral amastia is usually caused by Polands 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 amastia, the cause has not been well understood so far. It may be related to gene mutation since often patients with bilateral amastia are diagnosed as autosomal dominant and recessive inheritance. Decreasing blood flow in the subclavian artery may also be a cause of amastia.Amastia 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 amastia. Genetics
Congenital amastia can be associated with both autosomal dominant and recessive inheritance. However, in clinical research, autosomal recessive heritage amastia is uncommon.Mutation of genes may disrupt the normal process and results in abnormity of breast. The protein tyrosine receptor type F gene (PTPRF) is particularly important in nipple-areola region development. PTPRF encodes protein phosphatase which can localize at adherent junction. This phosphatase may also regulate epithelial cell to enable cell- cell interaction. PTPRF is also responsible for growth factor signalling and Wnt pathway.
Amastia refers to a rare clinical anomaly in which both internal breast tissue and the visible nipple are absent on one or both sides. It affects both men and women. Amastia can be either isolated (the only medical condition) or comorbid with other syndromes, such as ectodermal dysplasia, syndactaly (Polands syndrome) and lipoatrophic diabetes. This abnormality can be classified into various types, and each could result from different pathologies. Amastia differs from amazia and athelia. Amazia is the absence of one or both mammary glands but the nipples remain present, and athelia is the absence of one or both nipples, but the mammary gland remains.Amastia is presumably due to failure of embryologic (before birth) mammary ridge development or incomplete involution. People with amastia often suffer from ectodermal defects, which include various syndromes such as cleft palate, isolated pectoral muscle and abnormal formation of the arms.Treatment for female amastia particularly includes psychological guidance and breast reconstruction. Because there is no breast tissue, breastfeeding is not possible. If amastia only appears on one side, then it is possible to breastfeed on the other side. Often, people with amastia decide against treatment. Classification
Amastia can be either iatrogenic or congenital. The congenital amastia are further divided into syndromic type and non-syndromic type respectively. As the definition suggests, syndromic amastia is often associated with obvious symptoms. The common case is hypoplasia of ectodermal tissue, such as hair and skin defects. On the other hand, non-syndromic amastia, shows no defects in body parts other than breast.