Whole-body magnetic resonance imaging findings and patterns of chronic nonbacterial osteomyelitis in a series of Greek pediatric patients.

Background: Chronic nonbacterial osteomyelitis (CNO) is a pediatric autoinflammatory disorder presenting with sterile inflammatory bone lesions. Whole-body MRI (WBMRI) has most recently emerged for disease assessment, but data are limited. Purpose: The purpose is to evaluate the imaging findings and patterns of CNO on WBMRI in a series of Greek pediatric patients. Material and Methods: Whole-body magnetic resonance imaging studies of all children with documented CNO, performed in a single tertiary center, were retrospectively reviewed. WBMRI included coronal T1 and short-tau inversion recovery (STIR), whole spine sagittal STIR, and ankle/foot sagittal STIR images. High signal intensity lesions on STIR images corresponding to bone marrow edema were recorded. The SPSS v.20 statistical package was used for descriptive statistics. Results: Twenty children were included (mean age: 12, range: 6-16 years) with 1-31 lesions (mean: 11.8) on WBMRI. Two children had unifocal disease localized at the clavicle, three paucifocal (1-4 lesions), and 15 multifocal bone involvement. All but two children presented with ankle pain and exhibited lesions at the bones of the ankle joint (90%) followed by the knee (50%) and pelvis (10%). The tibia was the most frequently affected bone (70%) followed by calcaneus (60%), fibula (50%), femur (45%), talus, and metatarsals (45%). No lesions in the cervical, thoracic, lumbar spine, and mandible were documented. Only small sacral lesions were seen in 25% of patients with the extensive peripheral disease. Bilateral metaphyseal and epiphyseal involvement with transphyseal extension were common, but the periosteal reaction and well-defined lesion margins were rare. Conclusion: Frequent involvement of the foot and ankle and paucity of substantial spinal involvement were seen in Greek pediatric patients with CNO.