Abstract
Background: Traumatic bone cyst (TBC) is defined as a non-neoplastic osseous lesion and is considered a pseudocyst since it lacks an epithelial lining. There is a lack of understanding of the etiology and pathogenesis of this lesion. About 90%-95% of TBC cases involve the metaphysis of long bones. This article presented a case of TBC in the mandible.
Case Presentation: A 21-year-old male patient was presented with no history of trauma. Intra-oral examination revealed normal soft tissue. The lesion was asymptomatic and the teeth in the affected area responded normally to the vitality test. Orthopantomograph showed a well-defined unilocular radiolucent lesion, altered bone trabeculations with slightly increased bone density from the distal root of tooth # 46 to the distal root of tooth # 48, and mild thinning of the inferior mandibular borders. Cone-beam computed tomography showed a well-defined periapical lesion with a scalloping border around the roots at the same site and the inferior alveolar canal was displaced. The patient was draped and prepared for an incisional biopsy. A scant soft tissue and fragment of bony material were sent for histopathological examination to confirm the diagnosis. Microscopic examination of the specimen revealed a fragment of vital trabecular bone surrounded by fibrovascular connective tissue, and areas of hemorrhage were also observed that were managed by surgical curettage. Osseous regeneration was reported after 12 months of follow-up.
Conclusion: Swelling of the mandible without symptom in a young patient, with or without a trauma history would rise the suspension of a solit ary bone cyst.

Key words: Traumatic, bone, cyst, mandible, Saudi Arabia, case report.