ABSTRACT
Introduction Craniofacial microsomia, also termed hemifacial microsomia, is defined as a con
genital hypoplasia of the facial skeleton and soft tissues. There is no known genetic cause. It is thought to be due to an in utero vascular insult in the developing first or second branchial arches. It is unilateral in 90% of cases. After cleft lip and palate, this condition is one of the more common craniofacial congenital abnormalities. The incidence in the U.S. is estimated to be 1 in 5,000 births.
