Criteria of Bohan and Peter for the Diagnosis of Polymyositis and Dermatomyositis

• symmetrical proximal muscle weakness?

• elevations in the serum CK and aldolase?

• a skeletal muscle biopsy showing muscle degeneration, regeneration, necrosis, and phagocytosis, with an interstitial mononuclear cell infiltrate?

• a heliotrope rash on the face?

• Gottron's papules over joints?

• an erythematous and/or poikilodermatous rash?

• small amplitude, short duration polyphasic motor unit potentials?

• fibrillations, positive sharp waves, increased insertional irritability?

• spontaneous, bizarre high frequency (complex repetitive) discharges?

• peripheral or central nervous system involvement?

• sarcoidosis?

• active infection involving muscle?

• drugs or toxins associated with myopathy?

• rhabdomyolysis of known cause?

• metabolic disorders of muscle?

• presence of an endocrinopathy?

• muscular dystrophy?

• giant cell arteritis?

• myasthenia gravis?

• rubella vaccination?

• atheromatous or carcinomatous microembolization?

• Guillain-Barre syndrome?

• malnutrition?