Osteoradionecrosis Mimicking Medication-related Osteonecrosis of the Jaw in a Patient with Multiple Myeloma: A Case Report

Abstract

Background: Osteoradionecrosis of the jaw (ORNJ) and medication-related osteonecrosis of the jaw (MRONJ) may present with overlapping clinical and radiographic features, creating diagnostic difficulty in patients with complex oncological treatment histories. Case Presentation: A 61-year-old man with multiple myeloma and previous chemotherapy, antiresorptive therapy, corticosteroid therapy, and radiotherapy presented with painful swelling of the left mandibular region, a cutaneous fistula, and purulent discharge. Because of his medication history, MRONJ was initially considered. Subsequent disclosure by the patient’s attendant of radiotherapy to the left posterior mandible in 2021 changed the provisional diagnosis to osteoradionecrosis. Cone-beam computed tomography showed extensive osteolysis measuring approximately 40.3 mm and extending to the lower mandibular border. The patient underwent segmental mandibular resection, excision of the fistulous tract, extraction of teeth 33–42, and reconstruction using a reconstruction plate. Histopathological examination confirmed osteoradionecrosis of the left posterior mandible. Postoperative follow-up and orthopantomography showed satisfactory bone healing. Conclusion: The case demonstrates how incomplete treatment history can complicate differentiation between MRONJ and osteoradionecrosis in a patient with multiple myeloma. Repeated verification of oncological treatment history, together with clinical, radiographic, histopathological, and interdisciplinary assessment, was important in establishing the diagnosis and guiding management. The case also supports continued patient education and long-term follow-up because jaw necrosis can recur and may require ongoing assessment.