Treatment of Polymyositis in Children Under 18 Years of Age
Polymyositis occurring in patients under 18 is classified as juvenile-onset idiopathic inflammatory myopathy (IIM). This population has distinctive clinical features that set it apart from adult-onset disease, and its management requires input from paediatric specialists.
Paediatric-Specific Considerations
Juvenile-onset IIM differs from adult-onset disease in several clinically important ways — including a greater presence of subcutaneous calcification, less accumulated disease damage, absence of cancer association, an increased risk of vasculitis, and distinct autoantibody profiles. These differences mean adult protocols cannot simply be applied to this age group.
Treatment Goals
The central aim is early, complete control of muscle weakness and inflammation — sought specifically to improve long-term outcomes and reduce disease-related complications in this age group.
Treatment Approach
Induction involves high-dose glucocorticoid therapy, combined with an immunosuppressive agent as first-line treatment. A supervised exercise programme, led and monitored by a specialist physiotherapist and/or occupational therapist, is also a core component of management. The specific agents, dosing strategy, and sequencing are detailed in the full structured protocol.
References
- 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.
- High dose glucocorticoids should be used to treat active muscle inflammation at time of treatment induction.
- Management of IIM should include a safe and appropriate exercise programme led and monitored by a specialist physiotherapist and/or a specialist occupational therapist to improve quality of life and function.
- Early, complete control of muscle weakness and inflammation should be sought in juvenile-onset IIM, with the aim of improving outcomes and reducing disease-related complications.
DOI: 10.1093/rheumatology/keac115
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