Paediatric chronic recurrent multifocal osteomyelitis.

To cite: Wong DR, Wong GR, Moussa B, et al. BMJ Case Rep Published online: [please include Day Month Year] doi:10.1136/ bcr-2016-218957 DESCRIPTION A previously healthy girl aged 15 years presented with a 3-month history of low back pain, lethargy, morning stiffness and nocturnal back discomfort. She had no significant history of weight loss, infective symptoms or neurological symptoms, including bladder or bowel incontinence. There was no recent travel history. Examination revealed normal temperature and mild focal tenderness over the midline lumbar spine, with normal range of motion. There was isolated weakness in left hip flexion, and no other neurological findings. Blood tests showed a normal white cell count (6.6×10/L), elevated erythrocyte sedimentation rate (38 mm/hour) and slightly elevated C reactive protein (11 mg/L, normal<10 mg/ L). X-rays were unremarkable. A limited CT of L3 showed diffuse sclerosis of its spinous process with areas of lytic destruction and mild effacement of the paravertebral fat pads (figure 1). Serial blood cultures were negative for microorganisms. Subsequent empirical antibiotics with intravenous flucloxacillin were initiated for presumed infective osteomyelitis. Further assessment with MRI lumbar spine showed an abnormality at the L3 level, with expansion of the L3 lamina and spinous process, and an area of low T1 signal with corresponding high T2 signal within (figure 2). There was enhancement of this area postcontrast imaging, and adjacent paraspinal oedema without features of malignancy. Whole-body bone scan demonstrated focal abnormal uptake in the L3 spinous process, left sacral ala, left ilium and right proximal tibia (figure 3). Given the multifocality of the metabolically active bone lesions, combined with the relatively benign history and normal biochemistry, the diagnosis of chronic recurrent multifocal osteomyelitis (CRMO) was made. Antibiotics were ceased after 3 days and the patient underwent treatment with non-steroidal anti-inflammatory drugs (NSAIDs), followed by a tapering regimen of prednisolone 10 mg and physical therapy. At 6 months follow-up, she experienced a significant reduction in symptoms and improved quality of life. CRMO is a rare auto-inflammatory disorder which typically affects children (median age