title: Classification criteria for polymyositis and dermatomyositis.
abstract: OBJECTIVE
  The establishment of classification criteria for polymyositis (PM) and dermatomyositis (DM).
  
  
  METHODS
  Questionnaires inquiring about patients with DM, PM, systemic lupus erythematosus, progressive systemic sclerosis and noninflammatory neuromuscular diseases were distributed to the main medical institutes in Japan. Data were collected and analyzed by computer.
  
  
  RESULTS
  Among skin lesions of DM, heliotrope rash, Gottron's sign and erythema or purpura on the extensor surfaces of the extremity joints were shown to be distinguishing criteria. In both DM and PM, proximal muscle weakness, muscle grasping and spontaneous pain, nondestructive arthritis or arthralgia, elevated CK or aldolase level, presence of systemic inflammatory signs, myogenic changes on EMG, positive and anti Jo-1 antibody and pathologic findings compatible with inflammatory myositis were distinguishing criteria items.
  
  
  CONCLUSIONS
  When a patient satisfies one of 3 skin lesion items and at least 4 other items, he or she shall be classified as having DM, sensitivity 94.1%. When a patient satisfies at least 4 items other than skin lesion items, he or she shall be classified as having PM, sensitivity 98.9%. Specificity of DM and PM is 95.2%.
authors.affiliation: Service Center, University of Saitama.
authors.forename: K
authors.initials: K
authors.lastname: Tanimoto
authors.forename: K
authors.initials: K
authors.lastname: Nakano
authors.forename: S
authors.initials: S
authors.lastname: Kano
authors.forename: S
authors.initials: S
authors.lastname: Mori
authors.forename: H
authors.initials: H
authors.lastname: Ueki
authors.forename: H
authors.initials: H
authors.lastname: Nishitani
authors.forename: T
authors.initials: T
authors.lastname: Sato
authors.forename: T
authors.initials: T
authors.lastname: Kiuchi
authors.forename: Y
authors.initials: Y
authors.lastname: Ohashi
mesh_terms: D003882:Dermatomyositis / Q000145:classification* / Q000473:pathology / Q000503:physiopathology; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000473:pathology / Q000503:physiopathology; D009132:Muscles / Q000503:physiopathology; D009468:Neuromuscular Diseases / Q000473:pathology / Q000503:physiopathology; D017285:Polymyositis / Q000145:classification* / Q000473:pathology / Q000503:physiopathology; D012595:Scleroderma, Systemic / Q000473:pathology / Q000503:physiopathology; D012680:Sensitivity and Specificity; D012867:Skin / Q000473:pathology