Early surgical treatment in unilateral coronoid hyperplasia and facial asymmetry

Unilateral coronoid hyperplasia is a rare condition in the pediatric age. It may be an unrecognized cause of restricted mouth opening in children.The limited jaw movement is due to the enlargement of the coronoid process of the mandible that impinges on the zygomatic arch during mouth opening. This pathologic condition is still unknown and often misdiagnosed.Although in the past the term osteochondroma has been used to describe most of the unilateral and a few of the bilateral cases, there is no histologic evidence that the process has a neoplastic origin.Microscopic examination of the removed coronoid process has revealed hyperplastic compact bone covered with a thin layer of normal cartilage.There are multiple causes of mandibular hypomobility, each of them associated with different anatomic structures and etiologies, and a large number of cases, mostly bilateral, are idiopathic in nature.Several theories of pathogenesis have been proposed: temporomandibular joint dysfunctions, mandibular hypomobility, temporalis hyperactivity, hormonal stimulus, persistent cartilage growth center, genetic inheritance, and family factors.Unilateral coronoid hyperplasia is usually due to a trauma or a pathologic condition and is associated with facial asymmetry, being more frequently seen in women with histologic chondromatous or neoplastic changes. A thorough clinical history should include information about the onset and progression of pain and other subjective symptoms.In this study, we present a case of unilateral hyperplasia of the coronoid process in a 3 year-old female who, to the best of our knowledge, is the youngest patient so far reported with such anomaly.Our findings support the recommendation that early surgical treatment and aggressive postoperative physical therapy should be taken into account to allow for recovery of morphology and growth function in children.