Juvenile Dermatomyositis

Bohan and Peter developed the diagnostic criteria for juvenile myositis that is still considered standard today. However, researchers continue to develop and validate further tools to help in the diagnostic process and to avoid the more invasive muscle biopsy and electromyographic testing.

Bohan and Peter proposed the following: presence of three of the five findings listed below indicates probable myositis; four of the five, definite myositis. Juvenile dermatomyositis requires the skin changes (5).

  1. Proximal muscle weakness (upper or lower extremity and trunk); typically symmetric
  2. Elevated serum CK (creatine kinase) or aldolase level
  3. Muscle biopsy showing inflammation, damage or other characteristic changes in muscle tissue
  4. Myopathic changes on electromyogram (EMG)
  5. Skin rash
  • Heliotrope rash (reddish-purple erythema on the upper eyelids, often with edema)
  • Gottron's sign (reddish-purple nodules on the extensor surface of finger, elbow or other joints)

Further testing

Other blood tests used to diagnose or monitor juvenile myositis:

  • Antinuclear antibody (ANA)
  • Myositis-specific antibodies (MSA), i.e. anti-Jo-1, anti-SRP
  • Myositis-associated antibodies (MAA), i.e. anti-PM-Scl
  • Flow cytometry
  • Neopterin
  • von Willebrand factor antigen (factor VIII-related antigen)

Other diagnostic tools include:

  • Nailfold capillaroscopy, to study possible decreased density of nailfold capillary loops (dropout) or dilation of the capillaries
  • Manual muscle testing (MMT) and other tests of muscle strength
  • Tests for physical function, i.e. Childhood Health Assessment Questionnaire (CHAQ) and Childhood Myositis Assessment Scale (CMAS)

 

 

Updated March 2012

 
 
 

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