Imaging of refractory chronic recurrent multifocal osteomyelitis succesfully treated with etanercept and methotrexate

Methods A 5-year-old boy presented with a 1 year history of right leg pain with limited range of motion and difficulty in walking due to flexion, abduction and external rotation of right hip attitude. No fever. Plain radiographs were normal. In the blood test, elevation of acute phase reactants was detected: ESR 41 mm/h, CRP 2.27 mg/dL. A Whole Body MRI (WB-MRI) scan revealed osteitic multifocal lesions with edema and enhanced T2 signal without necrosis in: proximal epiphysis and metaphysis of right hip, proximal metaphysis of left femur, left isquium, left acetabular bottom, right acetabulum, sacrum and proximal metaphysis of right tibia. Intense bilateral sacroiliitis and mild synovitis in right hip were also observed. All this findings were suggestive of CRMO. Synovium biopsy showed chronic synovitis. Bone biopsy of femoral neck lesion was anatomopathologically compatible with CRMO with signs of acute inflammation. Cultures of both samples and synovial fluid were negatives. No infection or malignancy was identified in the extended study confirming the diagnosis of CRMO.