A 16-year-old girl presented with a 1-month history of a bony swelling in the body of the right mandible. The patient had undergone an endodontic procedure on the mandibular right first permanent molar (tooth #30) approximately 1 month previously for pain, swelling, and possible infection in the tooth. The swelling did not resolve after endodontic therapy, and she was referred to an oral surgeon for a biopsy. The patient’s medical history was noncontributory. Findings of the clinical examination revealed cortical expansion of the right mandibular body measuring approximately 2.0 cm in buccal/lingual dimension. The bone was covered by an intact mucosa without erythema or purulent drainage. Tooth #30 was clinically mobile, whereas the adjacent premolar and molar teeth were not mobile and tested vital. The patient denied experiencing paresthesia. A panoramic radiograph revealed a single, ovoid, unilocular radiolucency measuring 2.0 by 3.0 cm with distinct hyperostotic borders. The lesion surrounded the roots of tooth #30 and extended to the inferior border of the left mandibular body, involving the inferior alveolar nerve canal. The periodontal ligament space was symmetrically widened around the roots of tooth #30, with loss of the lamina dura and slight resorption of the mesial root apex. The interproximal crestal bone appeared intact both mesially and distally (Fig. 1).