A 9-year-old girl presented with a 3-month history of chronic right-sided lower facial swelling. (B–C) Three-dimensional cone-beam computed tomography scan and its reconstructed orthopantomogram revealed paracortical bone formation at inferior border of the mandibular angle and body. Because no odontogenic source was identified, an incisional biopsy was performed to rule out malignancy, which clinically demonstrated extracortical bone formation (D).