Aplasia of the First and Second Branchial Arches

The rare lethal syndrome of microstomia, aglossia, agnathia, and synotia (otocephalus, otocephalia) is the most severe form of the so-called first arch anomalies. A baby with this combination of malformations offered an opportunity to study the pathologic morphology of structures derived from first and second arch anlage. Although the pathologic anatomy varies from case to case, the observations of several authors along with our findings posed questions regarding the embryology of the midface, cranial base, and derivatives of the first two branchial arch structures. Current concepts require critical revision in order to logically classify the myriad of deformities that are presently designated first and second arch malformations.