Multiple Myeloma That Required Differentiation From Temporomandibular Joint Disorder: A Case Report

Multiple myeloma is characterized by a monoclonal neoplastic proliferation of plasma cells. This pathology can manifest as skeletal-related events (SREs), such as bone pain. However, such events are extremely rare in the mandibular condyle. We describe the case of an 82-year-old woman who presented to her dentist with occlusal pain in the right temporomandibular joint. Temporomandibular disorder (TMD) was diagnosed and treated using lifestyle modification. However, the pain did not subside, and she was referred to our department. On auscultation, crepitations were heard in the temporomandibular joint. Computed tomography showed an osteolytic lesion in the right mandibular condyle and cancellous bone loss in various locations. Abnormal ¹⁸F-fluorodeoxyglucose uptake was observed in the right mandibular condyle, among other locations. Blood testing revealed normocytic normochromic anemia, decreased renal function, delayed 1-h erythrocyte sedimentation rate, and decreased albumen and albumen-to-globulin ratio. Signal hyperintensity was evident in the right mandibular condyle on apparent diffusion coefficient mapping, while whole-body diffusion-weighted imaging with background body signal suppression revealed symmetrical diffusion-restricted areas in the right mandibular condyle, among other locations. These findings were diagnostic of multiple myeloma. The patient underwent chemotherapy, treatment for SREs, and oral care interventions to prevent medication-related osteonecrosis of the jaw (MRONJ). At present, the multiple myeloma remains stable, and TMD-like symptoms have disappeared. She can perform normal jaw movements, and no MRONJ has developed. Dentists must be aware that multiple myeloma can first present as orofacial manifestations. Care must be taken to avoid MRONJ when treating SREs of multiple myeloma.