Section Editor: Sandy Cheng-Yu Chen, M.D.
Taipei Medical University Hospital, Taipei, Taiwan
Hemifacial microsomia represents a spectrum of congenital craniofacial malformations, comprising anomalies arising from the first and second branchial arches and temporal bone primordia. This condition predominantly affects the ear, with preauricular appendages seen in A (arrows) and incomplete atresia of the left EAC (B, arrowhead); the oral cavity; and jaw, including a hypoplastic left mandibular ramus and zygomatic bone, and malformed coronoid (C, asterisk) and condylar processes (C, open arrow). Differential diagnosis includes Treacher Collins syndrome (bilateral involvement of facial structures is typical), Townes-Brocks syndrome (craniofacial abnormalities are rare), and CHARGE syndrome (constellation of congenital anomalies including coloboma and ear abnormalities, but also heart defects, choanae atresia, and genital hypoplasia).