What is dermatomyositis?

Dermatomyositis is a rare disease that causes muscle inflammation and skin rash. It’s one of a group of muscle diseases that cause muscle inflammation and swelling. It's different from other muscle diseases because it also causes inflammatory skin rashes. Dermatomyositis is the term used to describe both muscle and skin symptoms, but some people will have only one or the other.

It can occur at any age, but it most often affects adults ages 50 to 70. Women are twice as likely as men to be diagnosed with the disease. Some people with the disease also have a connective tissue disorder, such as lupus or rheumatoid arthritis.

What causes dermatomyositis?

The exact cause is not known, but possible causes include:

  • Abnormal genes you are born with
  • Cancer, especially in older people
  • Autoimmune disease, a type of illness that causes the body’s immune system to attack its own tissues
  • An infection, medicine, or another exposure in your environment that triggers the disease

What are the symptoms of dermatomyositis?

Swelling and inflammation in the blood vessels that supply your skin and muscles cause symptoms such as:

  • Red or purple rash on sun-exposed areas that may be painful or itchy
  • Red or purple swelling of the upper eyelids (heliotrope)
  • Red or purple spots on the knuckles, elbows, knees, and toes (Gottron's papules)
  • Joints that feel stuff and turn pale and painful in cold conditions and feel better when warmed (Raynaud's phenomenon)
  • Scaly, rough, dry skin, which can lead to hair thinning
  • Swollen, red areas around the fingernails
  • Hard lumps under the skin caused by calcium deposits (calcinosis)
  • Muscle weakness in the neck, hip, back, and shoulders
  • Trouble swallowing and voice changes
  • Tiredness, fever, and weight loss
  • Muscle aches
  • Trouble rising from a chair or getting out of bed due to muscle weakness

Sometimes the muscle inflammation can spread to other parts of the body including the heart, gastrointestinal tract, and lungs. Lung involvement can cause breathing trouble and coughing. Adults may have a low-grade fever, along with lung inflammation and sensitivity to light.

How is dermatomyositis diagnosed?

First your healthcare provider will ask about your medical history and do a physical exam.  He or she will look for an underlying disease, such as cancer. Your provider may also do the following tests:

  • Blood tests. These are done to look for signs of muscle inflammation. They also check for abnormal proteins that form in autoimmune disease. The most common blood tests include muscle enzyme creatine kinase and the antinuclear antibody.
  • Electromyelogram (EMG). This may be done to find abnormal electrical activity in affected muscles.
  • MRI. This test uses large magnets and a computer to look for inflammation in the body.
  • Skin or muscle biopsy. Tiny pieces of tissue are taken to be checked with a microscope.

How is dermatomyositis treated?

Treatment will depend on your symptoms, your age, and your general health. There's no cure for the condition, but the symptoms can be managed. You may need more than one kind of treatment. And your treatment may need to be changed over time. Treatments include:

  • Physical therapy. Special exercises help to stretch and strengthen the muscles. Orthotics or assistive devices may be used.
  • Skin treatment. You may need to avoid sun exposure and wear sunscreen to help prevent skin rashes. Your healthcare provider can treat itchy skin rashes with antihistamine drugs or with anti-inflammatory steroid creams for the skin.
  • Anti-inflammatory medicines. These are steroid drugs, or corticosteroids. They ease inflammation in the body. They may be given by mouth or through an IV.
  • Immunosuppressive drugs. These drugs block or slow down your body's immune system. 
  • Immunoglobulin. If you have not responded to other treatments, your provider may prescribe these medicines. They are donated blood products that may boost your body's immune system. They are put directly into your bloodstream through an IV.
  • Surgery. You may need surgery to remove the calcium deposits (calcinosis) under the skin if they become painful or infected.

Talk with your healthcare providers about the risks, benefits, and possible side effects of all medicines.


What are the complications of dermatomyositis?

Possible complications for some people with dermatomyositis include lung disease, heart disease, or cancer. These can make treatment more difficult.

Living with dermatomyositis

If you have dermatomyositis, you may need treatment for the rest of your life. It's important to learn as much as you can about the disease. Work closely with your healthcare provider. Researchers are studying causes and treatments for the condition. Early diagnosis and treatment for the disease may improve over time.

When should I call my healthcare provider?

If your symptoms get worse or you notice new symptoms, notify your healthcare provider.

Key points about dermatomyositis

  • Dermatomyositis is a rare disease that causes muscle weakness and skin rash.
  • Symptoms include a red or purple rash on sun exposed skin and eyelids, calcium deposits under the skin, muscle weakness, and trouble talking or swallowing.
  • There is no cure, but treatment is done to reduce the symptoms.
  • Complications include lung disease, heart disease, and cancer.
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