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

AIM: To explore the distribution patterns and extent of chronic recurrent multifocal osteomyelitis (CRMO) using whole-body magnetic resonance imaging (WBMRI). MATERIALS AND METHODS: 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. RESULTS: 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. CONCLUSION: 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. © 2019 The Royal College of Radiologists