A Large National Cohort of French Patients With Chronic Recurrent Multifocal Osteitis

Objective. To document more fully the characteristics of chronic recurrent multifocal osteomyelitis (CRMO) in pediatric patients, to collect data on the outcomes and management of the disease, and to define prognostic factors. Methods. One hundred seventy-eight patients were included (123 female patients and 55 male patients), with a mean +/- SD age at diagnosis of 10.9 +/- 2.9 years. Inclusion criteria were a diagnosis of CRMO, evidence of at least one lesion of osteitis confirmed by imaging, and development of the syndrome before age 18 years. Results. Longitudinal clinical and imaging studies revealed that only 12 of 178 CRMO patients (7%) had unifocal lesions at the last medical visit. We were able to apply the clinical chronic nonbacterial osteomyelitis score to 110 of 178 patients (62%), which indicated that bone biopsy could have been avoided in 27 cases (25%). At the last medical visit, disease was in remission in only 73 of 171 patients (43%) (41% receiving therapy) after a mean +/- SD of 47.9 +/- 38.9 months; 44 of 171 patients (26%) experienced sequelae. Using cluster analysis, the CRMO cohort was separated into 3 homogeneous phenotypes (severe, mild, and intermediate). Patients with the severe phenotype had the worst prognosis. This group was entirely composed of male patients, most of whom had the multifocal form of CRMO and inflammatory syndrome. Patients with the mild phenotype had the best prognosis. This group was primarily composed of female patients with a unifocal form of CRMO and infrequent clavicle involvement and inflammatory syndrome. Patients with the intermediate phenotype had a good prognosis but greater reliance on treatment. This group primarily included female patients with multifocal lesions and inflammatory syndrome. Conclusion. This is the largest CRMO cohort described in the literature to date. Clinical evolution and imaging investigations confirmed the multifocal pattern of the disease. Three distinct subgroups of CRMO patients were distinguished, with very different prognoses.