Polymyositis in patients under 18 years of age is a juvenile-onset inflammatory muscle disease that behaves differently from its adult counterpart and requires specialist paediatric management. This page addresses the treatment approach for children in whom initial therapy has failed to achieve early, complete control of muscle weakness and inflammation.
Juvenile-onset inflammatory myopathy should be managed by paediatric specialists, as it differs from adult-onset disease in several clinically important ways, including a greater presence of subcutaneous calcification, an increased risk of vasculitis, and different autoantibody associations.
The prior treatment line — corticosteroids (oral or intravenous) combined with methotrexate or mycophenolate mofetil, alongside a supervised exercise programme — did not achieve the goal of early, complete control of muscle weakness and inflammation. The protocol below describes the step taken at this point of escalation.
For children with refractory or severe muscle inflammation, the protocol considers specific agents, including intravenous immunoglobulin as one approach. The full selection criteria, additional treatment options, and the complete clinical algorithm are available in the structured protocol.
DOI: 10.1093/rheumatology/keac115
Juvenile-onset IIM should be managed by paediatric specialists as it differs from adult-onset IIM in several ways, including greater presence of subcutaneous calcification, less disease damage, lack of association with cancer, increased risk of vasculitis, and different autoantibody associations.
Intravenous immunoglobulin should be considered as a treatment of severe and/or refractory muscle inflammation.
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