Chronic Non-Bacterial Osteomyelitis in Children: A Retrospective Cohort Study From a Single Center

Abstract

Objective: Chronic nonbacterial osteomyelitis (CNO) is a rare autoinflammatory bone disorder characterized by sterile osteitis. This study aimed to evaluate the clinical, radiological, and therapeutic characteristics of pediatric patients with CNO and to analyze the evolving diagnostic and management strategies in a tertiary referral center. Materials and Methods: This retrospective single-center cohort study included 33 children diagnosed with CNO between 2018 and 2024. Demographic characteristics, clinical presentation, laboratory markers, magnetic resonance imaging (MRI) findings, treatment modalities, and outcomes were analyzed. Results: The cohort showed a slight male predominance (54.5%). The median age at symptom onset was 9 years (IQR 5.5–11.5), with a median diagnostic delay of 24 months. Multifocal involvement was observed in 81.3% of patients, with the femur (51.6%) and vertebrae (29.0%) being the most frequently affected sites. Whole-body MRI was used in 69.6% of cases, facilitating a relatively low bone biopsy rate (21.2%). Regarding treatment, although nonsteroidal anti-inflammatory drugs were used as initial therapy, 93.5% of patients required conventional disease-modifying antirheumatic drugs. Notably, 48.5% required escalation to anti-tumor necrosis factor agents due to disease recalcitrance or relapse. The relapse rate was 36.3% during a median follow-up of 37 months. Conclusion: Pediatric CNO presents with a heterogeneous phenotype. Our findings highlight a regional male predominance and a paradigm shift toward MRI-based diagnosis, reducing the need for invasive biopsies. The high utilization of biologic therapies underscores the refractory nature of the disease in tertiary care settings and supports a proactive, stepwise therapeutic approach to achieve sustained remission.