Osteomyelitis of the mandible exhibiting features of medication-related osteonecrosis in a patient with history of tocilizumab treatment

Osteomyelitis of the jaw of microbial origin manifests in bone with specific radiographic features that are key to the diagnosis. On occasion, other types of bone diseases like medication-related osteonecrosis of the jaw (MRONJ) need to be differentiated from either acute or chronic osteomyelitis. This is especially important if the medical history and physical examination are inconsistent. Apart from a thorough clinical examination, radiographic features hold an important role in the disease process which could ultimately lead to appropriate intervention. Clinician needs to be well-versed with the differential diagnosis of the bone lesions that might mimic osteomyelitis radiographically. Different medications can be attributed to osteonecrosis of the jaw (ONJ). Some monoclonal antibody medications have been attributed in the development of ONJ. Tocilizumab is a monoclonal antibody therapy used for rheumatoid arthritis. Tocilizumab-related osteonecrosis without history of bisphosphonate use has not been reported in the literature. We present a case of osteomyelitis that demonstrated similar radiographic and histological features of MRONJ in a patient treated with tocilizumab for rheumatoid arthritis without history of bisphosphonate use. Further studies are needed to assess relation between tocilizumab and ONJ.