Definition

Dermatomyositis is an inflammatory disease that results in skin changes and muscle weakness.

Causes

The exact cause is not known. It may be due to a problem with the immune system that causes it to attack healthy tissue. Genes and the environment may also play a role.

Risk Factors

This problem is more common in women. It often starts in people who are 30 to 50 years old.

Other things that may raise the risk are:

• Having certain genes
• Systemic lupus erythematosus
• Rheumatoid arthritis
• Scleroderma
• Certain cancers

Symptoms

Problems may be:

• A purple-red, itchy rash that may appear on the face, neck, trunk, fingers, or around joints
• Skin that is sensitive to sunlight
• Muscle weakness in the shoulder and hips
• Swelling of the skin
• Muscle pain
• Problems swallowing
• Swollen blood vessels

Diagnosis

You will be asked about your symptoms and health history. A physical exam will be done. You may be referred to a specialist for further evaluation.

Your bodily fluids and tissues may be tested. This can be done with:

• Blood tests
• Skin or muscle biopsy

Images may be taken of structures in the body. This can be done with:

• MRI scan or ultrasound
• CT scan

Muscles may be tested. This can be done with an electromyogram (EMG).

Lung function may be tested. This can be done with a pulmonary function test.

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Treatment

There is no cure. The goal of treatment is to manage symptoms and improve quality of life. Choices are:

• Physical therapy to improve muscle strength and flexibility
• Medicines to suppress the immune system, such as corticosteroids
• Lifestyle changes, such as exercising regularly and using sun protection

People with severe symptoms may be given immune globulin by IV. It contains antibodies that can block the unhealthy ones linked to dermatomyositis.

Prevention

There are no known guidelines to prevent this health problem.