Case of the Season: Asymmetric Chronic Recurrent Multifocal Osteomyelitis.

Chronic recurrent multifocal osteomyelitis is a rare noninfectious inflammatory bone disease diagnosed based on the synthesis of clinical, radiological, and pathological findings. The differential diagnostic considerations are led by multifocal infectious osteomyelitis and multifocal neoplasms. We report a case of a 9-year-old girl who emergently presented with worsening back pain, inability to walk, and normal vital signs. C-reactive protein and erythrocyte sedimentation rate were elevated, whereas the white blood cell count was normal. Initial radiographs and MRI of the spine showed multiple edematous vertebral body lesions. Subsequent whole-body MRI demonstrated multiple additional edematous bone lesions in the right half of the body, including the scapula, femur, and tibia. The lack of symmetrical bone lesion distribution indicated image-guided percutaneous core biopsy to exclude neoplastic disease. Pathological examination of an osseous core biopsy specimen showed a noninfectious osteomyelitis pattern with no findings of Langerhans cell histiocytosis, malignancy, or infectious osteomyelitis. The synthesis of clinical, radiological, and pathological findings was diagnostic of asymmetric right-sided chronic recurrent multifocal osteomyelitis, representing an atypical presentation that deviates from the typically symmetrical bilateral chronic recurrent multifocal osteomyelitis pattern.