Clinical and genetic association, radiological findings and response to biological therapy in seven children from Qatar with non-bacterial osteomyelitis.

AIM: We aim to report the clinical manifestations, genetic testing results, magnetic resonance imaging (MRI) findings and biologics used in the management of non-bacterial osteomyelitis in our center. METHODS: We conducted a retrospective review of medical records. A previously proposed classification was implemented as follows: chronic recurrent multifocal osteomyelitis (CRMO), chronic non-bacterial osteomyelitis (CNBO) and acute non-bacterial osteomyelitis. RESULTS: Four females and three males with a median age at presentation of 6 years (6 months-14 years) presented with arthralgia (7/7), back pain (4/7), arthritis (4/7) and bone pain (2/7). Six patients had CRMO and one patient had CNBO. Genetic testing revealed an apparent homozygote p.S734L LPIN2 mutation in two siblings, a heterozygote p.M694V MEFV mutation in one patient with familial Mediterranean fever and heterozygote p.Q219H PSTPIPI variant of unknown significance in one patient. The most common lesions on MRI involved the tibia (6/7), talar bones (5/7), fibula (4/7) and sacroiliac joints (4/7). Three patients received infliximab. Two are in remission after 2 and 5 years, and the third was advanced after 5 years to canakinumab. Two other patients received canakinumab first. One patient with Majeed syndrome and dyserythropoietic anemia exhibited evidence of improvement, and one had partial improvement and was then treated with infliximab. CONCLUSION: Non-bacterial osteomyelitis may coexist with other autoinflammatory diseases. MRI remains a favorable diagnostic tool and genetic testing may have a limited role in selected cases. Infliximab and canakinumab are associated with variable outcomes, and 6-week or less dosing intervals for both medications may be more effective.