Hemifacial hyperplasia is a rare morphological anomaly of the maxillofacial region characterized by unilateral overgrowth of all facial structures (bone, soft tissues, teeth), called true hemifacial hypertrophy, or overgrowth of one or more but not all facial structures, called partial hemifacial hypertrophy. It may be isolated or related to some syndromes (e.g. Beckwith-Wiedemann, Proteus, Klippel-Trenaunay-Weber, McCune-Albright syndrome, Neurofibromatosis type 1). It may be associated with airway obstruction, sensorineural hearing loss or swallowing difficulties. The disease is hemifacial hypertrophy (MONDO_0007590).