What Is Dermatomyositis?

Dermatomyositis affects muscles and the tissues around them. It also impacts blood vessels. This condition causes weakness and a skin rash. Most people who get it are between the ages of 60 and 80. Twice as many women get it as men.

It is not a common condition. Fewer than 10 of every 1 million people in the United States have it.

What Causes It?

Doctors aren’t exactly sure. 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.

What Are the Symptoms?

Changes in your skin and weakness in your muscles are the two main things that show up.

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 occur include:

Sometimes dermatomyositis causes calcium to build up in hard bumps under your skin or in a muscle. This may show up 1 to 3 years after your first symptoms start. Children are more likely to get calcium deposits than adults.

It also causes muscle weakness that gets worse over time. This happens first to the muscles closest to your center of your body, including those in your hips, thighs, shoulders, upper arms, and neck.

You’re usually weak on both sides of your body. You may also have joint pain, and your muscles may become thinner.

How Is It Diagnosed?

Your doctor has several tools she can use to figure out if you have dermatomyositis, including the following:


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 her if your muscles are damaged.

Chest X-ray. This can show whether your lungs are damaged, a possible sign of dermatomyositis.

Electromyography . This test looks at 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. She also can rule out other diseases, like lupus. This test can show whether your muscles are inflamed or damaged.

What’s the Treatment?

You can’t cure this condition, but you can treat your skin and muscle symptoms. You may need to see more than one doctor or medical professional, depending your symptoms. Any of the following specialists might play a part in your care:

  • Internist (for general care)
  • Rheumatologist (for problems with connective tissues such as muscles and joints)
  • Immunologist (for immune system problems)
  • Physical therapist (to help you regain muscle strength)
  • Speech therapist (to help you with speaking or swallowing problems due to muscle weakness)
  • Dietitian (forhelp finding easy-to-eat foods when swallowing is hard)

These are among the most common medications for dermatomyositis:

Other treatments that can help with muscle problems brought on by dermatomyositis include:

  • Heat therapy
  • Exercise
  • Orthotics
  • Devices that help you stand and move
  • Rest


Also, intravenous immunoglobulin (IVIg) is a treatment that pumps your body with healthy antibodies from donor blood through an IV. These antibodies block the unhealthy ones attacking your system.

In some cases, your doctor may suggest surgery to remove calcium deposits.

WebMD Medical Reference Reviewed by Debra Jaliman, MD on March 14, 2019



National Organization of Rare Disorders: “Dermatomyositis.”

Mayo Clinic: “Dermatomyositis.”

National Institute of Neurological Disorders and Stroke: “What is Dermatomyositis?”

Muscular Dystrophy Association: “Dermatomyositis (DM).”

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