Amastia refers to a rare clinical anomaly in which both breast tissue and nipple are absent. Amastia can be either isolated or complicated with other syndromes such as ectodermal dysplasia, syndactaly (Poland's syndrome) and lipoatrophic diabetes. This abnormity can be classified into various types and each could cause different pathologies. Amastia differs from amazia and athelia. Amazia refers to the absence of one or both mammary glands but the nipples remain present. While athelia refers to the absence of one or both nipples, but the mammary gland remains.