Table 1 Bohan and Peter’s criteria for diagnosis of dermatomyositis

Individual criteria

 1. Symmetric proximal muscle weakness

 2. Muscle biopsy evidence of myositis

 3. Increase in serum skeletal muscle enzymes

 4. Characteristic electromyogram pattern of myositis

 5. Typical rash of dermatomyositis

Diagnostic criteria

 • Definite: 5 plus any three of 1 to 4

 • Probable: 5 plus any two of 1 to 4

 • Possible: 5 plus any one of 1 to 4