Mysteries of Hemifacial Microsomia: What We Know and What We Don't

Hemifacial microsomia (HFM) is a congenital deformity of the face, characterized by a short mandible, ear dysplasia, facial nerve, and soft tissue dysplasia. The etiology of HFM is not fully understood, but potential causes include vascular malformation, Meckel's cartilage abnormalities, and cranial neural crest cell (CNCC) abnormalities. The commonly used clinical classification for HFM is OMENS, OMENS‐plus, and SAT, but other craniofacial anomalies like dental defects and zygomatic deformities are not precisely documented in the classification. Patients with severe HFM require multiple surgeries to address facial asymmetries, such as mandibular distraction osteogenesis (MDO), autologous costochondral rib graft (CCG), orthodontic and orthognathic treatment, and facial soft tissue reconstruction. Precise treatment for HFM may be possible with thoroughly documented phenotypes and a pathogenic diagnosis.