What is juvenile dermatomyositis?
Juvenile dermatomyositis (JDM) is an autoimmune disease that affects children, usually between the ages of 2 and 15. An autoimmune disease is one in which the body’s immune system attacks its own healthy tissues and cells because it mistakenly sees them as invaders.
What are the symptoms of juvenile dermatomyositis?
The main symptoms of juvenile dermatomyositis are skin rashes, usually on the face, knuckles, elbows, and knees, and swelling and weakening muscles. This is caused by inflammation in the blood vessels (vasculitis), and also by swelling in the muscles. Other symptoms may include:
- Red or purple coloring around the eyelids or cheeks
- Puffy eyelids
- Gradually weakening muscles (often in the neck, shoulders, trunk, back, or hips)
- Sore and swollen joints
- Difficulty with everyday activities, such as climbing stairs, standing up, riding a bicycle, getting dressed, lifting the head
- Frequently falling down
- Severe abdominal pain (because of ulcers in the digestive system due to the vasculitis)
- Weak voice (dysphonia)
- Difficulty swallowing (dysphagia)
- Hardened lumps from deposits of calcium underneath the skin (calcinosis)
- Muscle tightening and shortening, which can cause a joint to stay in a bent position
Because of these symptoms, the child may participate in fewer activities than other children. Sometimes the child may even be accused of being lazy.
How common is juvenile dermatomyositis?
Juvenile myositis (which includes both juvenile dermatomyositis and the very rare juvenile polymyositis) affects about 3,000–5,000 children in the United States each year.
What causes juvenile dermatomyositis?
The cause of JDM is not known. It does not spread from one person to another. Researchers believe it may be a result of the body’s abnormal immune system response to a virus. Even after the virus is gone, the immune system continues to fight and ends up attacking the body itself. Researchers also believe that autoimmune disorders such as JDM may be inherited.
How is juvenile dermatomyositis diagnosed?
Diagnosing JDM can be difficult because it is a relatively rare disease. In making a diagnosis, the doctor will do a general physical examination, as well as the following:
- Determining when skin rashes and muscle weakness first began to appear
- Tests of muscle strength
- Blood tests that look for enzymes or antibodies that contribute to muscle weakness or autoimmune disorders
- Magnetic resonance imaging (MRI), which uses a large magnet, radio waves, and a computer to produce images
- If necessary, muscle or skin biopsy, in which a sample of muscle or skin is removed and studied under a microscope for any abnormalities
How is juvenile dermatomyositis treated?
Treatment of JDM depends on how severe the disease is. The goals of treatment are to: control inflammation and prevent tissue damage; improve muscle strength; relieve pain; prevent other symptoms; and help the child and family live with the disease.
Some common treatments include:
- Corticosteroids (such as prednisone) – These drugs are usually used first. They help slow the body’s autoimmune response, thus reducing inflammation and pain and leading to improvement in muscle strength. Children are often started on high-dose intravenous (injected directly into the vein) corticosteroids, followed by regular oral or intravenous doses.
- Immunosuppressants (such as methotrexate, azathioprine, cyclosporine [Neoral or Sandimmune], tacrolimus [Prograf] or mycophenolate [Cellcept]) – These drugs work by quieting the immune system so that it doesn’t overreact. They are used alone or along with corticosteroids, when prednisone alone cannot control symptoms.
- Intravenous immune globulin (IVIG) – IVIG also helps quiet the immune response, actually by boosting it. This treatment is used for active skin disease or when other medications have been tried and have failed.
- hydroxychloroquine (Plaquenil) – This drug treats resistant rash.
- Bisphosphonates (Aledronate) – This drug helps improve calcinosis lesions.
- Biologic agents, drugs that work on a particular part of the immune system:
- Etanercept (Enbrel), adalimumab (Humira) and infliximab (Remicade) help reduce inflammation. Infliximab may be indicated for resistant calcinosis.
- Rituximab (Rituxan) targets B-cells, an immune system lymphocyte that produces antibodies that lead to inflammation.
A balanced diet, exercise, and physical therapy also play roles in treating JDM. In addition, because sunlight can make the rash worse, the child should use sunscreen when outdoors.
What can be expected following treatment for juvenile dermatomyositis?
Patients usually respond to treatments within one to two months. Muscle strength gradually returns in two to three months. Although special transportation services or supplies may be needed to provide assistance, the child should be able to attend a regular school and should not be isolated from others his or her own age.
The child may grow and mature more slowly than normal because the body is using its resources to balance fighting the disease and metabolizing required medications, and because the illness may affect his or her appetite.
What are the side effects of medications?
The side effects of medications for JDM include the following:
- Corticosteroids can cause weakened bones (osteoporosis), cataracts, upset stomach, weight gain, agitation, mood changes, and changes in blood sugar. For these reasons, corticosteroids are used only when necessary, and the dosage is reduced gradually over time.
- Immunosuppressants can cause nausea, fatigue, abdominal pain, and mild hair loss. Close monitoring is performed to prevent side effects to the kidney, liver, and blood counts, and there may be increased risk of future cancers. Immunosuppressants lower the body’s immune system, increasing one’s risk of getting an infection.
- Intravenous immune globulin may have acute side effects such as backache, headache, and fever. Intravenous immune globulin is expensive and requires repeated doses.
- Plaquenil may interfere with color vision over a long period of usage. The child should visit an eye doctor every 6-12 months while taking this drug.
- Biologic agents also increase one’s risk of infection. The body occasionally reacts to these medications by producing neurologic (brain), skin, or systemic inflammation. The treatments are expensive and are not always covered by insurance.
What is the long-term outlook for patients with juvenile dermatomyositis?
Most patients recover completely (remission), meaning that they no longer show signs of active disease or flareups. Yet there is a group of patients for whom treatment may not be 100% effective.
Patients who remain with longer periods of active disease are at higher risk of complications from calcinosis or from cardiopulmonary issues. Although most children recover completely, some will have permanent muscle weakness and stiffness.
Can developing juvenile dermatomyositis be prevented?
There is no known way to prevent the disease.
UpToDate. Pathogenesis and clinical manifestations of juvenile dermatomyositis and polymyositis. www.uptodate.com. Accessed August 8, 2011.
UpToDate. Diagnosis of juvenile dermatomyositis and polymyositis. www.uptodate.com. Accessed August 8, 2011.
UpToDate. Treatment and prognosis of juvenile dermatomyositis and polymyositis. www.uptodate.com. Accessed August 8, 2011.
The Myositis Association. Juvenile Dermatomyositis. www.myositis.org. Accessed July 17, 2011.
National Institutes of Health, Office of Rare Diseases Research. Genetic and Rare Diseases Information Center (GARD) – Juvenile dermatomyositis. rarediseases.info.nih.gov. Accessed July 17, 2011.
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