CASE PRESENTATION A 42-year-old man presented with a painful jaw. He had a past history of nasopharygeal carcinoma (NPC), and had been treated by irradiation two and a half years ago. On physical examination, there was swelling and a discharging sinus over the right side of the mandible. Radiographs of the mandible were obtained (Fig. 1). This was followed by computed tomography (CT) of the mandible (Figs. 2a and b). Technetium {Tc)-99m methylene diphosphonate (MDP) bone scintiscans were unremarkable apart from a solitary area of increased uptake in the right mandible. What do the radiograph and CT show? What is your diagnosis? Fig. 2 Enhanced axial CT scans of the mandible taken with (a) bone and (b) soft tissue settings.