Juvenile dermatomyositis (JDM) is a rare disease that causes muscle inflammation and a skin rash. It's different from other muscle diseases because it also causes skin problems. Symptoms often first appear in children between ages 5 and 10. Children with JDM have weak muscles around the neck, shoulders, upper arms, thighs, and hips. They also have a skin rash around areas such as the eyelids, knuckles, and finger joints.

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Doctors don't know the exact cause of this condition. But it may be linked to problems with the immune system that cause inflammation in the muscles and blood vessels.

JDM symptoms often appear slowly over time. In some cases, they may happen more quickly or severely. Each child's symptoms may vary. The most common symptoms can include:

• Fever.
• Violet or dusky red rash around the eyelids, knuckles, or finger joints.
• Rash on the elbows, knees, and ankles.
• Progressive muscle weakness.
• Lack of energy (fatigue).
• Ill feeling (malaise).
• Muscle pain and soreness.
• Irritable mood.
• Trouble swallowing.
• Weight loss, from trouble swallowing.
• Joint pain and inflammation.
• Hardened deposits under the skin (calcinosis).
• Mouth ulcers.
• Muscles wasting away (muscle atrophy).
• Muscles that become paralyzed in a contracted position.
• Voice changes.
• Stomach ulcers.

Your child's doctor will ask about your child's health history and do a physical exam. Your child may also have tests such as:

• Blood tests. These tests are used to check for antibodies, muscle enzymes, and signs of inflammation.
• Electromyelogram. This is an electrical test that may be done to find nerve or muscle damage.
• MRI. This test uses large magnets and a computer to look for inflammation in the body.
• Muscle and skin biopsy. Tiny tissue samples are removed and checked under a microscope.

Treatment will depend on your child's symptoms, age, and general health. It will also depend on how bad the condition is. There is no cure for JDM. But the symptoms can be managed. The disease may go into remission. This means the symptoms will go away. Treatments may include:

• Medicines. These are used to treat inflammation and skin symptoms.
• Physical, speech, and occupational therapy. This can help to improve muscle function and strength. Assistive devices may also be prescribed.
• An exercise program. This also can improve muscle function and strength.
• Sunscreen. This helps prevent more irritation or damage to the skin.
• Nutrition. A healthy diet will help support the body's health during the disease.
• Vitamins and other supplements. These can also help support the body's health.

Talk with your child's doctor about the risks, benefits, and possible side effects of all treatments.

Many children will recover from JDM without any lasting problems. Some children may have trouble moving because of shortening of the joints (contractures). Other children may have ongoing (chronic) symptoms. These may include pain, muscle weakness, and delayed growth. There may be damage to bones, joints, lungs, and other internal organs.

JDM can make it hard for a child to take part in school and other activities. Work with your child's school to help teachers and caregivers understand your child's limits. A healthy lifestyle can help improve your child's quality of life. This includes a good diet, exercise, and rest. A support group may help your child feel less alone or different.

Contact the doctor if your child has any of these:

• Symptoms that don't get better or get worse
• New symptoms