Radiological diagnosis of chronic recurrent multifocal osteomyelitis using whole-body MRI-based lesion distribution...

To explore the distribution patterns and extent of chronic recurrent multifocal osteomyelitis (CRMO) using whole-body magnetic resonance imaging (WBMRI).

Children with established diagnoses of CRMO, who had undergone WBMRI, had their images reviewed by three radiologists using a novel pictorial mapping system for determining lesion load and distribution patterns.

Thirty-seven children (mean 12 years; range 2-18 years) had 317 lesions (8.6 lesions per patient [LPP]; range 2-27). Multifocal involvement was noted in 33 (89%) and unifocal in four (11%). The tibia was most frequently involved (68% of patients; 29% of lesions). Clavicular involvement was noted in 38% and spinal lesions in 19% of patients. Bilateral disease involved the fibulas (80%), tibias (68%), and foot phalanges (67%) most frequently. In 93% of bilateral disease, there was also symmetry. A "tibio-appendicular multi-focal pattern" (tibial but no clavicular involvement) was present in 54% whereas a "claviculo-spinal pauci-focal pattern" (clavicular lesions, no tibial involvement; few additional lesions mainly of the spine) was present in 24%. Only 14% had synchronous involvement of the clavicle and tibia. In the long bones, 65% of lesions were metaphyseal (distal metaphysis 42%) and 35% epiphyseal (173 peri-physeal lesions). Epiphyseal lesions were minimal in 60% whereas metaphyseal lesions were extensive in 75%. Sixty-six percent of tibial symmetric lesions and 100% of symmetric lesions of the radius, humerus, and ulna were of equal severity.

CRMO lesions are often multifocal and can have typical long bone distal metaphyseal locations. Two main phenotypic patterns have emerged: multifocal predominantly tibial involvement or pauci-focal clavicular and spinal disease.