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Juvenile Dermatomyositis

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What Is Juvenile Dermatomyositis?

Juvenile dermatomyositis (JDM) is a long-term disease in which a child's muscles, skin, and sometimes other organs become inflamed or damaged.

What Causes Juvenile Dermatomyositis?

Juvenile dermatomyositis (dur-meh-toe-my-oh-SYE-tis) is an autoimmune disease. This means that the infection-fighting immune system gets “confused” — instead of destroying germs, it attacks the body's cells and tissues.

The exact cause of JDM isn't known but a child's genetics and environment likely play a part.

What Are the Signs & Symptoms of Juvenile Dermatomyositis?

JDM can cause different symptoms, including:

  • weakness: Muscles in the upper arms, upper legs, neck, and belly slowly get weaker over time. A child might have trouble raising their arms above their head to ask a question or to brush their hair. They may need help when walking up stairs or standing up from a sitting position.
  • skin changes: Kids with JDM may have different skin rashes, including purple color and swelling over the eyelids, red rash over their nose and cheeks, small bumps over the knuckles, or hard deposits of calcium under their skin.
  • other symptoms: such as fevers, weight loss, and tiredness

How Is Juvenile Dermatomyositis Diagnosed?

To help them diagnose JDM, doctors can:

  • get a medical history and do an exam: doctors ask about symptoms and the child's past health, and do an exam
  • order blood work: some types of blood tests can help make a diagnosis, especially if results show signs of muscle inflammation
  • get imaging tests: an MRI, typically of the thighs, can look for inflammation in the muscles
  • rarely, other tests (like taking a sample of the muscle or measuring the electrical activity of the muscles)

How Is Juvenile Dermatomyositis Treated?

Juvenile dermatomyositis is a lifelong disease, but treatments can help get it under control and even into remission. Doctors treat it with medicines to suppress the immune system. This often takes 1–2 years, if not longer. Close monitoring by a primary care provider and a pediatric rheumatologist is important. Physical therapy may also help to strengthen the person's muscles.

How Can Parents Help?

If your child has juvenile dermatomyositis:

  • Make sure your child takes all medicines exactly as directed.
  • Work with the physical therapist to develop a regular exercise program. This will help your child regain lost strength and keep that strength for the future.
  • Make sure your child always wears sunscreen, even on days that aren't very sunny. UV rays from the sun can trigger a flare-up of JDM.
  • Learn about JDM with your child. Your care team is a great resource.

You also can find more information and support online at:

Date reviewed: March 2022