Multiple myeloma in the lower jaw developing subsequently after mandibular medication-related osteonecrosis of the jaw: a case report

Multiple myeloma is a hematologic malignancy characterized by the presence of abnormal clonal plasma cells in the bone marrow, with the potential for uncontrolled growth causing destructive bone lesions, kidney damage, anemia, and hypercalcemia.Bisphosphonates are a group of drugs that have been used successfully in the treatment of diseases associated with osteoclast-mediated bone loss, e.g. for the treatment of bone metastases in malignant diseases including Multiple Myeloma.However, in multiple myeloma patients taking bisphosphonates, an incidence of Bisphosphonate-associated osteonecrosis of the jaw (BAONJ) of 1.8-12.8%has been reported.BAONJ occurs only in the jawbones, and MM can also affect the jaw.The two diseases have similar clinical and radiological manifestations.There are several cases in the literature of MM masquerading as BAONJ, which were initially clinically diagnosed as BAONJ but were later histologically confirmed as MM.The simultaneous diagnosis of MRONJ and MM at the same site is rarely reported.In our report, the patient was clinically and histologically diagnosed as BAONJ, but 2 years later, MM was detected radiographically at the site of BAONJ development.