Chronic recurrent multifocal osteomyelitis is a differential diagnosis of juvenile idiopathic arthritis

A 5 year old girl was referred to the paediatric rheumatology clinic in June 1999 for assessment of possible juvenile idiopathic arthritis (JIA). She had been well until seven months previously, when she began to limp and developed a swollen left ankle. At this time she appeared generally unwell and irritable but had no history of fever or rashes. There was no previous past medical history of note. She lived with her parents and twin brother, who were all well. A distant relative was believed to have rheumatoid arthritis. A full blood count was normal, C reactive protein and blood cultures were negative. A radiograph of the left ankle showed a lucency at the distal tibia with associated periosteal reaction (fig 1). A technetium-99m MDP bone scan showed increased uptake in the lower end of the left tibia (fig 2A) as well as the body of L5 and the left sternoclavicular joint (fig 2B). A biopsy of the lower end of the left tibia showed evidence of necrosis and new bone formation with much inflammation and fibrosis, but little suppuration (fig 3). No organisms were identified and culture of the biopsy was negative. Figure 1 An x ray picture of the left ankle. Adjacent to the tibial epiphysial plate of the left ankle, there is an area of osteolysis of the tibial metaphysis (black arrows). This is associated with a periosteal reaction (white arrowhead). Figure 2 (A) Three phase 99mTc MDP bone scan, static view shows increased uptake in the distal end of the left tibia (arrow). (B) Three phase 99mTc MDP bone scan, static view also shows a small focus of increased uptake at the right aspect of L5 (arrow) and the left sternoclavicular joint. Figure 3 Biopsy of left tibial lesion showing an area of dead bone (large arrow), an …