Objectives: This multicenter cohort study aimed to describe the clinical and demographic features of pediatric patients diagnosed with Chronic Non-Bacterial Osteomyelitis (CNO) in Turkey and to identify patient clusters based on bone involvement.
Methods: A total of 334 pediatric CNO patients from 21 pediatric rheumatology centers were included. Data on clinical presentation, imaging, and biopsy results were collected. A two-step cluster analysis was performed to classify patients by bone-site involvement, resulting in four distinct clusters.
Results: Axial-thoracic cluster, involving the vertebra, clavicle, and sternum, was more common in female patients and showed higher rates of skin involvement. Lower-extremity cluster, characterized by lower extremity bone involvement, included the largest number of patients. Unlike previous reports, the Turkish cohort had a higher proportion of male patients and a lower frequency of skin involvement. At a median follow-up of 42.4 months, 77.3% of patients achieved remission, while 22% experienced relapse. Mandibular involvement, additional rheumatologic diseases, and localized bone pain were associated with increased relapse risk.
Conclusions: This study highlights the clinical profile of pediatric CNO in Turkey, marked by male predominance and low skin involvement. The identified bone-site clusters may help guide prognosis and should be validated in other populations.
Keywords: autoinflammatory bone disease; chronic non-bacterial osteomyelitis; chronic recurrent osteomyelitis; cluster; pediatric.
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