Ten-year review of Danish children with chronic non-bacterial osteitis.

Objectives: To compare clinical characteristics of children with chronic non-infectious osteomyelitis (CNO) with either mono- or multifocal bone lesions, and to report potential advantages of using whole-body MRI.

Methods: A retrospective evaluation of 31 children (19 girls, 12 boys) diagnosed with CNO between 2001 and 2011. CNO was diagnosed as mono-, or multifocal inflammatory bone lesions (osteomyelitis, osteitis, osteosclerosis), duration of complaints more than 6 weeks and exclusion of infection and malignancy. Clinical and radiological data were registered. The definition of mono- or multifocality was based on the description of imaging results.

Results: Mean age at disease onset was 10.3 ± 2.6 years. Mean duration of active disease was 44.4 ± 25.6 months. Twenty-two (71.0%) had two or more bone lesions and 9 (29.0%) had one lesion. Of those with multifocal lesions six were initially detected as monofocal. The most frequent location of the bone lesions was in the metaphysis of the lower extremities. MRI/CT discovered most lesions compared to x-ray and scintigraphy. MRI was performed in 93.5% of which 25.8 % had a whole-body-MRI. Whole-body MRI revealed disclosure of several silent lesions. Extra-osseous involvement occurred in 64.5%. In the multifocal group 22.7 % had psoriasis and 13.6 % had pustulosis palmoplantaris but neither was seen in the monofocal group. All were treated with NSAIDs; 54.8% corticosteroids, 29.1 % methotrexate, 9.7 % pamidronate and 3.2 % infliximab.

Conclusions: Monofocal CNO had comparable clinical and radiological characteristics to multifocal disease. We conclude that whole-body MRI is a relevant screening instrument for the diagnosis of CNO.