Paeds · rheumatology-musculoskeletal-and-sports
Juvenile dermatomyositis
Also known as Juvenile dermatomyositis · JDM · Childhood dermatomyositis · Juvenile idiopathic inflammatory myopathy
Fellowship guide to juvenile dermatomyositis: the child with a heliotrope rash and Gottron papules who cannot climb stairs, the Bohan and Peter and 2017 EULAR and ACR classification criteria, the myositis-specific antibodies that define phenotype and prognosis, methotrexate with corticosteroids as first-line therapy, calcinosis and lipodystrophy as the long-term damage, and the CARRA, PRINTO and UK consensus treatment pathways.
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- A child with progressive proximal weakness and a heliotrope or Gottron rash has juvenile dermatomyositis until proven otherwise — check the creatine kinase immediately and start treatment early, because delayed therapy drives calcinosis and permanent damage
- Anti-MDA5 juvenile dermatomyositis carries a high risk of rapidly progressive interstitial lung disease, cutaneous ulceration and oral ulcers — request a high-resolution chest CT and lung function early, even when the child looks predominantly cutaneous
- Dysphagia, nasal speech or a weak cough signal pharyngeal and respiratory muscle involvement with a real risk of aspiration — arrange speech and language assessment and a videofluoroscopy, and protect the airway before escalating immunosuppression
- Calcinosis affects up to four in ten children and is the single greatest source of long-term morbidity — the best treatment is prevention through prompt, aggressive control of disease activity in the first months
- A transaminitis in a weak child may be coming from muscle rather than liver — alanine aminotransferase and aspartate aminotransferase are released by inflamed muscle, so do not be falsely reassured about hepatic function
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Board mappings
- Recognise the rash and weakness of juvenile dermatomyositis
- First-line investigations: creatine kinase and muscle MRI
- Bohan and Peter and 2017 EULAR and ACR classification criteria
- Myositis-specific antibodies and their phenotypes
- Corticosteroid plus methotrexate first-line therapy
- The weak child with a rash — a written favourite
- Calcinosis and lipodystrophy as long-term damage
- Long case: a child with established juvenile dermatomyositis on immunosuppression
- Short case: heliotrope rash, Gottron papules and proximal weakness
- Level 2 — recognises multisystem autoimmune disease
- Level 3 — investigates and co-manages juvenile dermatomyositis
- Applied knowledge: classification and antibody phenotypes
- Treatment with methotrexate and corticosteroids
- Short case: dermatomyositis rash and muscle examination
- Communication: explaining chronic immunosuppression
- General Pediatrics — multisystem rheumatic disease
- Subspecialty: Pediatric Rheumatology — juvenile dermatomyositis
- Patient Care: recognise and refer juvenile dermatomyositis
- Medical Knowledge: inflammatory myopathy and vasculopathy
- Systems-Based Practice: multidisciplinary rheumatology, dermatology and physiotherapy care
- Medical Expert — inflammatory myopathies of childhood
- Collaborator — multidisciplinary juvenile dermatomyositis care
Overview & Definition
Picture the six-year-old girl who, over three weeks, has become unable to climb the school bus steps, needs both hands to push herself up from a chair, and has developed a violaceous flush around her eyes and scaly red patches over her knuckles. No single finding is unique, but the combination of that rash with progressive proximal weakness is juvenile dermatomyositis, and the window to prevent permanent damage is already open. [4]
Juvenile dermatomyositis is the commonest idiopathic inflammatory myopathy of childhood, an immune-mediated small-vessel vasculopathy that targets skin and skeletal muscle and, less often, the gut, lungs and heart. It differs from the adult disease in its vasculopathic biology, its high rate of calcinosis and its near-absence of malignancy association, and it replaces earlier labels such as childhood dermatomyositis. Modern classification leans on the 2017 EULAR and ACR criteria that fold in muscle biopsy, magnetic resonance imaging and myositis-specific antibodies, alongside the older Bohan and Peter framework that many examination questions still use. [1] [2]
Three ideas anchor the topic for a fellowship candidate. The diagnosis rests on pattern recognition of a characteristic rash with proximal weakness, supported by muscle enzymes and imaging rather than on any single blood test. Treatment is corticosteroid plus methotrexate given promptly, and the intensity of early therapy predicts whether the child escapes calcinosis and lipodystrophy. And the myositis-specific antibody defines a clinical subgroup that changes both the differential and the prognosis, from the steroid-responsive anti-Mi-2 child to the anti-MDA5 child at risk of interstitial lung disease. [5] [12]
References12ShowHide
- [1]Lundberg IE, Tjärnlund A, Bottai M, et al. 2017 European League Against Rheumatism/American College of Rheumatology classification criteria for adult and juvenile idiopathic inflammatory myopathies and their major subgroups. Ann Rheum Dis, 2017.PMID 29079590
- [2]Bohan A, Peter JB Polymyositis and dermatomyositis (first of two parts). N Engl J Med, 1975.PMID 1090839
- [3]Bohan A, Peter JB Polymyositis and dermatomyositis (second of two parts). N Engl J Med, 1975.PMID 1089199
- [4]Huber AM Juvenile dermatomyositis: advances in pathogenesis, evaluation, and treatment. Paediatr Drugs, 2009.PMID 19877722
- [5]Rider LG, Nistala K The juvenile idiopathic inflammatory myopathies: pathogenesis, clinical and autoantibody phenotypes, and outcomes. J Intern Med, 2016.PMID 27028907
- [6]Ruperto N, Pistorio A, Oliveira S, et al. Prednisone versus prednisone plus ciclosporin versus prednisone plus methotrexate in new-onset juvenile dermatomyositis: a randomised trial. Lancet, 2016.PMID 26645190
- [7]Tansley SL, Simou S, Shaddick G, et al. Autoantibodies in juvenile-onset myositis: their diagnostic value and associated clinical phenotype in a large UK cohort. J Autoimmun, 2017.PMID 28663002
- [8]Hoeltzel MF, Oberle EJ, Robinson AB, et al. The presentation, assessment, pathogenesis, and treatment of calcinosis in juvenile dermatomyositis. Curr Rheumatol Rep, 2014.PMID 25366934
- [9]McCann LJ, Juggins AD, Maillard SM, et al. The Juvenile Dermatomyositis National Registry and Repository (UK and Ireland)—clinical characteristics of children recruited within the first 5 yr. Rheumatology (Oxford), 2006.PMID 16567354
- [10]Huber AM, Giannini EH, Bowyer SL, et al. Protocols for the initial treatment of moderately severe juvenile dermatomyositis: results of a Children's Arthritis and Rheumatology Research Alliance Consensus Conference. Arthritis Care Res (Hoboken), 2010.PMID 20191521
- [11]Shah M, Mamyrova G, Targoff IN, et al. The clinical phenotypes of the juvenile idiopathic inflammatory myopathies. Medicine (Baltimore), 2013.PMID 23263716
- [12]Rider LG, Shah M, Mamyrova G, et al. The myositis autoantibody phenotypes of the juvenile idiopathic inflammatory myopathies. Medicine (Baltimore), 2013.PMID 23877355