The traumatic bone cyst (TBC) is an uncommon and poorly understood entity. First described in 1929, by definition, TBCs lack an epithelial lining. These lesions most frequently occur in the jaw. 1 Although most often asymptomatic, rarely a TBC can lead to a pathologic fracture of the mandible. 2,3 Only a few such cases appear in the literature. In this report, we present a case of an adolescent suffering a sports-related pathologic mandible fracture secondary to a TBC.Facial fractures in the pediatric population are uncommon. Less than 15% of all facial fractures occur in the pediatric population. 4 The most common site for a mandible fracture in children is the condyle, accounting for $45% of fractures. 4,5 Motor vehicle accidents account for nearly 60% of mandible fractures. 5 Only 2% of mandible fractures in children are caused by sports injury. 5 Case ReportA 13-year-old adolescent boy presented to our Emergency Department (ED) with persistent facial pain following a collision while playing football. During practice, the patient was struck in the chin with a teammate's knee. He was wearing a helmet, mouth guard, and football pads at the time. He was initially evaluated at an outside hospital, where a computed tomography (CT) scan was performed and identified a significantly displaced left-sided parasymphyseal mandible fracture. He was referred initially to a local surgeon as an outpatient, but presented to our ED the following day.The Otolaryngology-Head and Neck Surgery department was consulted upon arrival to our ED. Physical examination revealed tenderness of the left side of the mandible and a visible intraoral step-off between the left mandibular lateral incisor and canine tooth. The CT was reviewed and demonstrated a significantly displaced fracture of the left parasymphysis. The fracture was deemed pathologic secondary to an apparent preexistent cystic lesion of the mandibular symphysis measuring 2.5 Â 1.5 Â 1.5 cm, with evidence of bony expansion (►Fig. 1).The patient was taken to the operating room the next day. With evidence of a lesion in the mandible of unknown pathology, the decision was made to proceed with a transcervical approach to provide broader access that would allow for adequate curettage and resection if needed. The fracture line and cystic cavity were identified. A cystic lumen was filled with organized blood clotlike material. No definitive solid tissue was identified (►Fig. 2). The clot and the cortex of the cavity were curetted and sent for histologic interpretation. Occlusion had been established previously with maxillomandibular fixation. The mandibular fracture was reduced and repaired with a lower-border Synthes Matrix mandibular locking bar with bicortical screws (Synthes CMF, West Chester, PA). An additional 2.0 Synthes Matrix monocortical plate was used to secure a sizable secondary fragment of the cystic wall (►Fig. 3). The cystic space was packed with Gelfoam (Pfizer, Pharmacia and Upjohn Company, Kalamazoo, MI), as a means of filling the cystic dead space with a Keywords ...