Comparative study of radio-clinical parameters in pediatric forms of fibrous dysplasia and chronic recurrent multifocal osteomyelitis.

Chronic recurrent multifocal osteomyelitis (CRMO) is an autoinflammatory disease with clinical and radiological symptoms that overlap with fibrous dysplasia (FD), particularly in children. This study aimed to compare the clinical and radiological features of craniofacial CRMO and FD in a pediatric population. Seven children with CRMO and 14 with FD were retrospectively identified in our tertiary centre between 2012 and 2022. Their clinical, radiological, and biological (when available) data were collected. Two experienced radiologists reviewed imaging modalities following a standardized form, including characteristics of the lesions, soft-tissue involvement, and signal abnormalities (MRI). Swelling and pain were common symptoms in the CRMO group (7/7 and 5/5, respectively), compared with 11/14 and 2/14 patients in the FD group. Imaging (CT scan) comparisons revealed a predominance of erosive lesions, cortical interruption, periosteal apposition, and soft-tissue involvement in CRMO compared with FD (4/5 vs 0/6, p1 = 0.01; 5/5 vs 1/6, p2 = 0.01; 5/5 vs 0/6, p3 = 0.002; and 4/5 vs 0/6, p4 = 0.02, respectively). Hyperosteosis was mainly associated with FD lesions (6/6 vs 2/5, p = 0.06). Knowledge of the clinical and radiographic differences between CRMO and FD could help clinicians to differentiate between the two diseases.