Definition

Dermatomyositis is a muscle disease that causes inflammation and a skin rash. It is a type of inflammatory myopathy.

Causes, incidence, and risk factors

The cause is unknown. Experts think it may be due to a viral infection of the muscles or a problem with the body's immune system.

Anyone can develop dermatomyositis, but it most commonly occurs in children age 5 to 15 and adults age 40 - 60. Women develop this condition more often than men.

Polymyositis is a similar condition, but the symptoms occur without a skin rash.

Symptoms

• Muscles weakness, stiffness, or soreness
• Purple-red skin rash
• Purple or violet colored upper eyelids
• Muscle weakness
• Difficulty swallowing
• Shortness of breath

The muscle weakness may appear suddenly or occur slowly over weeks or months. You may have difficulty raising your arms over the head, rising from a sitting position, and climbing stairs.

The rash may appear over the face, knuckles, neck, shoulders, upper chest, and back.

Signs and tests

The doctor will perform a physical exam. Tests may include:

• Bloods test to check levels of creatine phosphokinase and aldolase
• ECG
• Electromyography
• Magnetic resonance imaging (MRI)
• Muscle biopsy

Treatment

The disease is treated with anti-inflammatory medicines called corticosteroids and drugs that suppress the immune system.

When your muscle strength gets better, your doctor may tell you to slowly cut back on your doses. However, most persons with this condition must take a medicine called prednisone indefinitely.

If the condition is associated with a tumor, the muscle weakness and rash may improve when the tumor is removed.

Support Groups

Expectations (prognosis)

Some people may recover and have symptoms completely disappear. Doctors have reported several such cases, especially in children.

In adults, death may result from severe and prolonged muscle weakness, malnutrition, pneumonia, or lung failure. The major causes of death are cancer (malignancy) and lung disease.

Complications

• Acute renal failure
• Cancer (malignancy)
• Inflammation of the heart
• Joint pain
• Lung disease

Calling your health care provider

Call for an appointment with your health care provider if you have muscle weakness or other symptoms of this condition.

Prevention

Images

References

Goldman L, Ausiello D. Goldman: Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders; 2007.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org). URAC's accreditation program is an independent audit to verify that A.D.A.M. follows rigorous standards of quality and accountability. A.D.A.M. is among the first to achieve this important distinction for online health information and services. Learn more about A.D.A.M.'s editorial policy, editorial process, and privacy policy. A.D.A.M. is also a founding member of Hi-Ethics and subscribes to the principles of the Health on the Net Foundation (www.hon.ch.)

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. ©1997-2008 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.