Hemifacial Microsomia Review: Recent Advancements in Understanding the Disease.

Hemifacial microsomia (HFM) is the second most common congenital disability of the face, with a prevalence of 1 in 3000 to 5600 live births. Although etiology is still not fully understood, including both genetics and environmental factors, the latest reports indicate the prominence of premature loss of the neural crest cells. What is more, a deficit of muscles of mastication, except the masseter, correlates in the pathomechanism of mandibular underdevelopment. Due to the significant phenotypic diversification, the typical picture of HFM cannot be determined. It may present as an esthetic concern-minor asymmetry with deformed auricle, and on the contrary, as microtia/anotia with conductive type hearing loss, hypoplastic mandible, and microphthalmia, impairing patient's daily activities. Referring to psychosocial problems, it has been proved that in population with HFM, there is a modestly elevated risk for behavior problems, social competence, and less acceptance. Over the years, more comprehensive methods of assessing the extent and severity of the HFM as the OMENS (+) classification have emerged. The authors like to summarize and present for plastic surgery resident and plastic surgeons the critical features of HFM, including the epidemiology, clinical presentation, pathogenesis, and innovative management reported in the current literature.