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Most common pediatric inflammatory myopathy; Bohan and Peter diagnostic criteria (definite JDM: heliotrope rash or Gottron papules plus at least three criteria; probable JDM: heliotrope rash or Gottron papules plus two criteria)

  • Heliotrope rash (eyelids) or Gottron papules (extensor surfaces)

  • Progressive symmetric proximal muscle weakness

  • Elevated skeletal muscle enzymes (creatine phosphokinase, aspartate aminotransferase [AST], aldolase, lactate dehydrogenase [LDH])

  • Electromyogram (EMG) consistent with myopathy

  • Biopsy evidence of myositis

  • Updated criteria will likely include muscle abnormalities on MRI short T1 inversion recovery (STIR) or T2 sequence


  • Incidence: About 2–3 cases in 1 million children

  • Peaks at 4 to 9 years of age

  • Girls > boys (2:1)

  • Unlike in adults, JDM has no definite associations with malignancy in children.


  • Potential infectious triggers: Group A beta-hemolytic Streptococcus, coxsackievirus B, parvovirus, Epstein–Barr virus (EBV), others

  • HLA and tumor necrosis factor α (TNF-α) alleles may predispose a child to JDM.

  • Molecular mimicry is suspected.

  • Sun exposure may trigger onset of rash.

Differential Diagnosis

  • Rheumatologic

    • ✓ Juvenile polymyositis is rare in children (2–8% of inflammatory myopathies) and has a higher age at onset and a more severe disease presentation, includes proximal and distal weakness and muscle atrophy, and lacks skin abnormalities; calcinosis is rare.

    • ✓ Systemic lupus erythematosus (SLE) and related conditions (e.g., mixed connective tissue disease, Sjögren syndrome)

    • ✓ Systemic Sclerosis

    • ✓ Juvenile idiopathic arthritis; polyarticular or systemic

    • ✓ Polyarteritis nodosa

    • ✓ Eosinophilic fasciitis

  • Infectious

    • ✓ Viral myopathies: Influenza, coxsackievirus, echovirus, parvovirus, EBV, herpes simplex virus, parainfluenza virus, adenovirus, enterovirus

    • ✓ Bacterial and parasitic myopathies: Staphylococcus, Streptococcus, Toxoplasma, Trichinella

  • Metabolic/genetic

    • ✓ Muscular dystrophies

    • ✓ Congenital myopathies

    • ✓ Myotonic disorders

    • ✓ Glycogen storage diseases

    • ✓ Periodic paralysis

    • ✓ Endocrinopathies

  • Other

    • ✓ Trauma

    • ✓ Toxins

    • ✓ Drug-induced myopathies

    • ✓ Disorders of neuromuscular transmission


  • Autoimmune angiopathy

  • Perivascular inflammation, mostly mononuclear cells

  • Swelling and blockage of capillaries, tissue infarction, perifascicular atrophy

  • Chronic inflammation ensues, with fibrosis and microscopic calcification

Clinical Manifestations

  • Proximal muscle weakness (neck flexors, shoulders, abdomen, thighs): Gower sign, difficulty climbing stairs or combing hair

  • Skin: Heliotrope rash (violaceous rash of eyelids); facial erythema, possibly in malar distribution (with involvement of nasolabial folds in contrast to SLE); papulosquamous eruption on extensor surfaces (Gottron rash), particularly over interphalangeal joints; shawl sign (erythematous rash in a shawl distribution); cutaneous calcinosis and ulceration

  • Nailfolds: Capillary drop-out, capillary dilation, cuticular hypertrophy

  • Arthritis: Can be transient or persistent, with or without tenosynovitis, flexor nodules; flexion contractures due to myofascial inflammation

  • Mucocutaneous: Oral ulcers, gingival inflammation

  • Pulmonary: Shortness of breath, cough, crackles can be consistent with interstitial lung disease or aspiration pneumonia.

  • Gastrointestinal (GI): Dysphagia, enteric ulceration with or without perforation, bleeding, constipation, diarrhea, abdominal pain

  • Other manifestations: Lipodystrophy, polyneuropathy, retinal exudates, and cotton wool patches

  • Other ...

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