Aplasia cutis congenita after methimazole exposure in utero; a case report and literature review

Aplasia Cutis Congenita [ACC] is a rare disorder with a complicated pattern of| inheritance. Babies are born with the absence of certain layers of skin. It most commonly manifests as a solitary defect on the scalp, but sometimes it may occur as multiple lesions. The affected area is typically covered with a thin, transparent membrane. The skull and/or underlying areas may be visible and be abnormally developed. ACC may be the primary disorder or it may occur in association with other underlying disorders. This article presents a case of ACC in a newborn whose mother was treated with methimazole due to thyrotoxicosis during the first trimester of pregnancy. He was born term with midline scalp defects. This case report is presented to highlight the steps to successful management and review the relevant literature. Management strategies are based on the size and presence of an underlying skull defect. A review of the literature seems to support the hypothesis that methimazole is a potential teratogen. Although the risk of birth defects is low with clinically applied doses of the drug, it cannot be regarded as safe and should therefore be avoided pregnant women. Propylthiouracil should be considered as the first choice drug for hyperthyroid pregnant women until further data on the safety of methimazole are available