Nonossifying fibroma (metaphyseal fibrous defect) of the mandible in a 15-year-old boy.

We describe a rare case of nonossifying fibroma of the mandible in a 15-year-old boy who presented with a left mandibular swelling. Conventional imaging showed an expansile radiolucent lesion involving the angle and the body of the left mandible. The lesion was curetted, and a miniplate was implanted at the excision site. Microscopic examination of the removed specimen revealed a cellular lesion characterized by a proliferation of uniform spindle-shaped cells in a vague but prominent storiform pattern, which represented the classic appearance of nonossifying fibroma. Three months later, radiography detected a fracture of the implantation plate. The area was re-explored with curettage of the soft tissue, which on microscopy demonstrated findings similar to the initial curettage findings. Follow-up radiology revealed satisfactory healing of the jaw, and no further recurrence was seen 2 years after the initial surgery. We present this case to highlight the importance of recognizing nonossifying fibroma in the mandible, which can be easily confused with more common mandibular lesions.