Hemifacial Microsomia

Hemifacial microsomia, also known as unilateral otomandibular dysostosis or lateral facial dysplasia, is a congenital malformation characterized by asymmetry of the first and second branchial arches. This condition is the 2nd most common craniofacial anomaly after cleft lip and palate. The terms "hemifacial microsomia" and "craniofacial microsomia" are often used interchangeably. However, craniofacial microsomia refers more broadly to any asymmetrical development of the craniofacial skeleton, including ipsilateral skull base hypoplasia. In contrast, hemifacial microsomia most commonly describes maxillary-mandibular hypoplasia involving the pharyngeal arch structures described. For consistency, this activity will use the term hemifacial microsomia (HFM) throughout. Patients typically present with unilateral hypoplasia of the ear, facial skeleton (including the maxilla, mandible, zygoma, and temporal bones), and surrounding soft tissue, although bilateral cases have been reported (see . Bilateral Hemifacial Microsomia). HFM and Goldenhar syndrome, also known as Goldenhar-Gorlin syndrome, are considered variants within the same clinical continuum of disorders, termed the oculoauriculovertebral spectrum. Goldenhar syndrome includes HFM phenotypes along with epibulbar dermoid and vertebral anomalies.