Aplasia Cutis Congenita after Methimazole Exposure in Utero; A case Report and Literature Review

Objective: Aplasia Cutis Congenita (ACC) is a rare disorder with a complicated pattern ofinheritance. Babies are born with the absence of certain layers of skin. It most commonlymanifests as a solitary defect on the scalp, but sometimes it may occur as multiple lesions. Theaffected area is typically covered with a thin, transparent membrane. The skull and/or underlyingareas may be visible and be abnormally developed. ACC may be the primary disorder or it mayoccur in association with other underlying disorders.Case presentation: This article presents a case of ACC in a newborn whose mother was treatedwith methimazole due to thyrotoxicosis during the first trimester of pregnancy. He was bornterm with midline scalp defects. This case report is presented to highlight the steps to successfulmanagement and review the relevant literature.Conclusion: Management strategies are based on the size and presence of an underlying skulldefect. A review of the literature seems to support the hypothesis that methimazole is a potentialteratogen. Although the risk of birth defects is low with clinically applied doses of the drug, itcannot be regarded as safe and should therefore be avoided pregnant women. Propylthiouracilshould be considered as the first choice drug for hyperthyroid pregnant women until further dataon the safety of methimazole are available.