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In July 2004, we reviewed a 21 month old Anglo-Caribbean child who presented to our paediatric unit with a limp of his left leg. He had no history of trauma and was otherwise asymptomatic. Blood tests were normal apart from a raised erythrocyte sedimentation rate (ESR) of 15 mm/h, rising to 34 mm/h over a four week period.
Plain radiograph of his left foot revealed an osteolytic lesion in the anterior calcaneum, which was confirmed by computed tomography (CT) scan (fig 1). Examination and culture of bone biopsy specimens were negative and he improved with non-steroidal anti-inflammatory drugs (NSAIDs).
Chronic recurrent multifocal osteomyelitis (CRMO) is a rare inflammatory disorder of unknown cause characterised by periods of exacerbation interspersed by remissions.1 It primarily affects the skeletal system though extra-skeletal sites can be affected. The commonest sites are metaphyses of long bones, spine, pelvis, and shoulder girdle.
The gold standard for diagnosis of CRMO is histopathology of bony lesions. Lesions consist of chronic inflammatory cells and cultures are characteristically negative.2 Plain radiographic findings are variable. CRMO can present as an osteolytic, sclerotic, or a mixed lytic-sclerotic lesion. Magnetic resonance imaging scans have been used to evaluate the activity of lesions and to identify the most appropriate site for biopsy. In our patient the bony lesion was confirmed by CT scan as this was more readily available.
NSAIDs are the treatment of choice. Azithromycin has been used in the treatment of this condition because of its anti-inflammatory and immuno-modulatory effects. Oral steroids, bisphosphonates, and sulfasalazine have also been used in specific cases.
The long term outcome of CRMO is poorly understood. Long term sequelae include school difficulties, bony deformities, psoriasis, and inflammatory bowel disease.3
We conclude that CRMO is an important differential of childhood limp and should be considered in a persistent case of limp when other common causes have been excluded.
Competing interests: none