Retrospective Analysis of Children with Chronic Non-bacterial Osteomyelitis

Objective: Chronic non-bacterial osteomyelitis (CNO) is a rare autoinflammatory bone disorder which mainly affects children and young adolescents. In this study, we report our single-center experience with pediatric CNO patients. Method: Children diagnosed with CNO at the Department of Pediatric Rheumatology of Hacettepe University between November 2006 and July 2021 were retrospectively reviewed. The demographics, clinical features, laboratory findings, imaging modalities, concomitant diseases, and treatments were recorded. Diagnostic delay was defined as the time interval from symptom onset to diagnosis. Results: A total of 48 patients (52.1% male) with a median age of 13.7 (minimum-maximum: 3.3-20.4) years were included. Local bone pain was the most frequent symptom (72.9%), followed by arthralgia (52.1%), limping or difficulty in walking (43.8%), and back pain (33.3%). Elevated erythrocyte sedimentation rate (52.1%) and high C-reactive protein levels (43.8%) were the most frequently observed laboratory abnormalities. Magnetic resonance imaging (MRI) (regional MRI in 87.5% and whole-body MRI in 66.7% of patients) was widely used in the diagnosis. Non-steroidal anti-inflammatory drugs (NSAIDs) were used in all patients and six patients (12.5%) achieved complete clinical remission with NSAIDs alone. Methotrexate (MTX) (80.9%), biological agents (7.1%), and pamidronate (11.9%) were used as the second-line treatment. Also, 26.4% of patients achieved clinical remission with MTX. Biological treatment was required in a total of 27 patients (56.2%). Conclusion: Local bone pain is a warning sign for CNO diagnosis. Complete clinical remission can be achieved in CNO patients with an escalating anti-inflammatory treatment, having NSAIDs in one end, and biological drugs and bisphosphonates on the other end of the spectrum.