Monofocal Nonbacterial Osteitis of the Distal Radius in Children: A Case Report

Abstract

Introduction: Chronic bacterial osteitis is a rare inflammatory disease in children that can mimic certain tumor lesions, particularly eosinophilic granuloma. Forms localized to a single site, particularly at the lower end of the radius, are uncommon and make the diagnosis difficult. Observation: A 7-year-old girl was referred for chronic pain in her right forearm. X-rays showed a metaphyseal cystic lesion of the lower end of the radius, associated with significant thinning of the cortex. Magnetic resonance imaging initially suggested an eosinophilic granuloma due to a well-defined lesion, with hypersignal on water-sensitive sequences and hyposignal on T1-weighted sequences, without collection or soft tissue invasion. This suspicion of a tumor led to a bone biopsy. The examination revealed a weakened cortex containing a clear, non-hematic fluid. The pathological study revealed non-specific inflammatory osteitis, and microbiological samples were negative, leading to a diagnosis of chronic non-bacterial osteitis. Treatment with anti-inflammatory drugs led to rapid improvement. Radiology showed gradual filling of the lesion, with complete healing after one year. Conclusion: This observation illustrates a monofocal form of chronic non-bacterial osteitis mimicking an eosinophilic granuloma on imaging. Biopsy remains essential to rule out a tumor or infectious lesion. The prognosis is favorable with anti-inflammatory treatment.