Aplasia cutis congenita and other anomalies associated with methimazole exposure during pregnancy.

Aplasia cutis congenita (ACC) is a congenital defect consisting of a circumscribed absence of skin that usually involves the scalp. The etiology is uncertain, and several teratogenic agents such as methimazole have been involved. We report two cases of ACC and other anomalies in newborns exposed to methimazole during pregnancy.