Dermatomyositis is a muscle disease that involves inflammation and a skin rash. It is a type of inflammatory myopathy.
The cause of dermatomyositis is unknown. Experts think it may be due to a viral infection of the muscles or a problem with the body's immune system. It may also occur in people who have cancer in the abdomen, lung, or other parts of the body.
Anyone can develop dermatomyositis. It most often occurs in children age 5 to 15 and adults age 40 to 60. Women develop this condition more often than men.
Polymyositis is a similar condition, but the symptoms do not include a skin rash.
Symptoms may include:
The muscle weakness may come on suddenly or develop slowly over weeks or months. You may have trouble raising your arms over your head, getting up from a sitting position, and climbing stairs.
The rash may appear on your face, knuckles, neck, shoulders, upper chest, and back.
Exams and Tests
The health care provider will do a physical exam. Tests may include:
The disease is treated with anti-inflammatory medicines called corticosteroids. You may also take drugs to suppress the immune system such as methotrexate, azathioprine, and hydroxychloroquine to treat the skin rash.
If the condition does not respond to these medicines, other drugs that suppress the immune system may be tried.
When your muscles get stronger, your doctor may tell you to slowly cut back on your doses. Most people with this condition must take a medicine called prednisone for the rest of their lives.
If a cancer is causing the condition, the muscle weakness and rash may get better when the tumor is removed.
Symptoms may go away completely in some people, such as children.
The condition may be fatal in adults due to severe muscle weakness, malnutrition, pneumonia, or lung failure. The major causes of death with this condition are cancer and lung disease.
Complications may include:
When to Contact a Medical Professional
Call your health care provider if you have muscle weakness or other symptoms of this condition.
Jorizzo JL, Vleugels RA. In: Bolognia JL, Jorizzo JL, Schaffer JV, et al, eds. Dermatology. 3rd ed. Philadelphia, PA: Elsevier Mosby; 2012:chap 42.
Reviewed By:Gordon A. Starkebaum, MD, professor of medicine, division of rheumatology, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.
The information provided herein should not be used during any medical emergency
or for the diagnosis or treatment of any medical condition. A licensed medical professional
should be consulted for diagnosis and treatment of any and all medical conditions. Call 911
for all medical emergencies. Links to other sites are provided for information only -- they
do not constitute endorsements of those other sites. © 1997-A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.
The Agency for Health Care Administration (Agency) and this website do not claim the information on, or referred to by, this site is error free. This site may include links to websites of other government agencies or private groups. Our Agency and this website do not control such sites and are not responsible for their content. Reference to or links to any other group, product, service, or information does not mean our Agency or this website approves of that group, product, service, or information.
Additionally, while health information provided through this website may be a valuable resource for the public, it is not designed to offer medical advice. Talk with your doctor about medical care questions you may have.