About Juvenile Dermatomyositis

Juvenile dermatomyositis (JDM) is an inflammatory, autoimmune disease that primarily affects skin, muscles, and joints.

  • Peak age of onset: 7 yo
  • Range: 1-15 yo

Clinical Presentation

  • Muscle weakness is a prominent symptom, not myalgia
  • Vast majority of patients with JDM have skin disease
  • Dermatomyositis in children is rarely associated with malignancy
  • Bones are often weak due to chronic inflammation and/or steroid therapy

Management

  • Sunscreen is important in preventing disease flare.

MSK Exam

  • Muscle weakness primarily in proximal limb-girdle, neck, and trunk

Skin

Other Organ Involvement

  • Respiratory (interstitial lung disease)
  • GI (dysphagia, aspiration, intestinal vasculopathy)
  • Cardiac (cardiomyopathy)

Lab Workup

  • Muscle enzymes: CK, AST, ALT, LDH, aldolase
  • CRP and ESR not markedly elevated

Imaging

  • MRI w/o contrast to look for muscle enhancement, muscle atrophy and/or fatty infiltration
  • X-rays can show calcinosis in extremities
  • Other inflammatory myopathies
    • Juvenile polymyositis
    • Myositis associated with other connective tissue diseases (e.g. lupus)
    • Post-infectious myopathy
  • Non-inflammatory myopathy:
    • Muscular dystrophy
    • Metabolic myopathy
    • Thyroid dysfunction

Pharmacologic

Non-Pharmacologic

  • Physical therapy
  • Occupational therapy
  • Suncreen
  • Monitor for other organ involvement (cardiac, lung, GI)
  • Early treatment to prevent:
    • Joint contractures
    • Irreversible skin damage
    • Appropriate growth of mm and bones
  • Risk for osteopenia and pathologic fractures from steroids