Chronic Nonbacterial Osteomyelitis

Abstract

Chronic nonbacterial osteomyelitis (CNO) is a rare inflammatory disorder that primarily affects children. It is characterized by insidious onset of pain, local bone expansion, and radiological findings suggestive of osteomyelitis, usually at multiple sites. CNO predominantly affects metaphyses of long bones, but clavicle and mandible are suggestive of diagnosis. CNO is a diagnosis of exclusion, and its pathogenesis is still unknown. Differential diagnosis includes infections, malignancies, benign bone tumors, metabolic disorders, and other autoinflammatory disorders. Biopsy of the bone lesion is often required. Nonsteroidal anti-inflammatory drugs are the first choice of treatment. Alternative therapies have been used, including corticosteroids, methotrexate, bisphosphonates, and TNFα inhibitors. No guidelines exist on diagnostic and treatment options.