How is dermatomyositis diagnosed?

How is dermatomyositis diagnosed?

Dermatomyositis is usually diagnosed with blood tests and biopsies of your skin and muscles.

Your provider will test your blood for:

• Increased amounts of specific muscle enzymes that means something is damaging them.
• Autoantibodies (cells that show your immune system is reacting to something it detects as harmful).

You’ll also need a skin biopsy of any rashes. Your provider might also biopsy your muscles to confirm inflammation inside them.

You might need one of a few imaging tests. Your provider will use these to evaluate your muscles, nerves, lungs and other organs. These tests can help them determine if your symptoms are caused by dermatomyositis or another issue. The most common imaging tests used to diagnose dermatomyositis include:

• Magnetic resonance imaging (MRI).
• Chest X-rays.

In some cases, your provider may request an electromyography (EMG). This test measures electrical activity in response to muscle or nerve stimulation.