Classification of myositides

1. Big picture

Myositides are inflammatory diseases of skeletal muscle. They belong to the broader group of skeletal muscle diseases, together with muscular dystrophies, non-inflammatory myopathies and ion-channel disorders.

The key clinical pattern is:

Subacute or chronic proximal muscle weakness, often with muscle pain, raised CK and inflammatory markers, without sensory loss.

In neurology exams, myositis must be distinguished from:

• myasthenia gravis;
• muscular dystrophy;
• motor neuron disease;
• polyneuropathy;
• radiculopathy;
• endocrine/toxic/drug-induced myopathy.

The most important myositis types are:

1. Polymyositis
2. Dermatomyositis
3. **Inclusi