Dermatomyositis is an autoimmune disorder. It affects the skin and muscle. It also impacts blood vessels. This condition causes muscle weakness and a skin rash.

Causes of Dermatomyositis

  • Doctors aren’t exactly sure what causes it. It may come from a gene or be triggered by your environment, or both.

  • It acts mostly like an autoimmune disorder. That means your body mistakes its own tissues as the enemy and attacks itself.

  • When you have dermatomyositis, your immune system goes after the blood vessels inside your muscles and the connective tissues in your skin.

Symptoms of Dermatomyositis

A dermatomyositis rash is easy to spot. It’s patchy and purple or red in color. It shows up on your eyelids and anywhere you use muscles to straighten joints, including your:

  • Knuckles

  • Elbows

  • Knees

  • Toes

This rash is typically the first sign. You may get other rashes, too, which typically are red and show up on your:

  • Face

  • Neck

  • Shoulders

  • Upper chest

  • Back

  • Your skin may look like it’s sunburned. It can feel scaly, dry, and rough.

Other things that can happen include:

  • Weight loss

  • Low-grade fever

  • Inflamed lungs

  • Sensitivity to light

Diagnosis of Dermatomyositis

Blood tests

After taking a little bit of your blood with a needle, your doctor will send it to a lab to see if you have high levels of certain enzymes. This can tell them if your muscles are damaged.

Chest X-ray

This can show whether your lungs are damaged, a possible sign of dermatomyositis.


This test looks at the electric output of your muscles to see where the weakness is. Your doctor puts a thin needle with an electrical impulse into your muscle, then records how much electric output there is when you tighten and relax.

Magnetic resonance imaging (MRI)

Your doctor will use this to see where your muscles are inflamed.

Biopsy of your skin or muscle

By removing a small part of your skin and looking at it under a microscope, your doctor can see if you have dermatomyositis. They also can rule out other diseases, like lupus. This test can show whether your muscles are inflamed or damaged.

Treatment of Dermatomyositis

  • Corticosteroids, such as prednisone. You take these by mouth or through an IV.

  • Corticosteroid-sparing agents. These help lower the amount of corticosteroid you need, and that cuts down on your side effects. They include azathioprine (Azasan, Imuran), methotrexate (Trexall) and mycophenolate mofetil (Cellcept).

  • Immunosuppressant drugs, such as azathioprine and methotrexate. These help reduce your inflammation if prednisone doesn’t work.

  • Rituximab (Rituxan) is a rheumatoid arthritis medication.

  • Antimalarial medicines like hydroxychloroquine (Plaquenil) treat rashes that won’t go away.

At home, things that can help with muscle problems brought on by dermatomyositis include:

  • Sunscreen

  • Heat therapy

  • Exercise

  • Orthotics

  • Devices that help you stand and move

  • Rest

  • A regular routine

  • Educating yourself about your illness

  • Following your treatment plan

  • Recognizing your feelings

diseases treatments health prevention muscular-system disorders dermatomyositis

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