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(Idiopathic Inflammatory Myopathy)

Pronounced: Der-MAA-toe-MY-oh-SI-tis

En Español (Spanish Version)


Dermatomyositis is a noninfectious inflammation of muscle tissue and skin.

Dermatomyositis and its sister disease, polymyositis , belong to a large category of connective tissue disorders that include lupus erythematosus , rheumatoid arthritis , and scleroderma (systemic sclerosis).

They are all believed to represent “autoimmune disorders,” where the body launches an attack against its own tissue. These chronic, progressive conditions lead to tissue destruction. They are potentially serious conditions that require care from your doctor. The sooner these disorders are treated, the more favorable the outcome. If you suspect you have dermatomyositis, contact your doctor immediately.


Although the cause or causes are not known, a viral infection may trigger the onset of dermatomyositis by causing the body’s immune system to misidentify infected skin and muscle tissue as a threat.

Risk Factors

The following factor increases your chance of developing dermatomyositis:

  • Having another connective tissue disorder


If you experience any of these symptoms, do not assume it is due to dermatomyositis. These symptoms may be caused by other, less serious health conditions. If you experience any one of the following symptoms, see your physician.

  • Weakness
    • Especially of the hips and thighs (making it difficult to climb stairs or stand)
    • May also occur in arms or neck
  • Aching pain in legs, shoulder, arm, or neck
  • Tender muscles
  • Difficulty swallowing
  • Violet-colored, bumpy, or scaly skin rash (especially around the eyes, upper back, elbows, or knuckles)
  • Itching, especially the scalp
  • Photosensitivity (skin burning or itching upon exposure to sunlight)
  • Aching and color changes (red, white, and blue) in fingers, especially in cold temperatures
  • Joint pain
  • Shortness of breath


Your doctor will ask about your symptoms and medical history, and perform a physical exam. You are likely to be referred to a rheumatologist (a doctor who specializes in musculoskeletal disorders).

Tests may include the following:

  • Blood tests
  • Electromyogram (EMG)—to test the electrical responsiveness of your muscles. This test involves inserting tiny needles into affected muscles and stimulating them with tiny electrical currents.
  • Muscle biopsy—surgical removal of a small piece of muscle to examine it under a microscope
  • Magnetic resonance imaging (MRI) or ultrasound—to help detect inflammation in your muscles
  • Skin biopsy—surgical removal of a small piece of skin to examine it under a microscope
  • Cancer tests—in adults, associated with cancer about 15% of the time, may be the first sign of cancer
  • CAT scan (CT)—a type of x-ray that uses a computer to make pictures of structures inside of the body, in this case the chest (Dermatomyositis may be associated with lung disease.)

Skin Biopsy

Skin proceedure

© 2008 Nucleus Medical Art, Inc.


Talk with your doctor about the best treatment plan for you. Treatment options include the following:

General Health Maintenance

Because dermatomyositis is a serious disease with long-term implications, physical exercise, a healthy lifestyle, and a nutritious diet are an integral part of treatment.


Cortisone-like drugs, usually oral prednisone, often produce a satisfactory response over the course of 2 to 3 months, after which the dose may be reduced according to the activity of the disease.

Immunosuppressive Drugs

Agents used to treat cancer and organ transplants have helped patients who did not respond to prednisone. Examples of these medications include:

  • Methotrexate
  • Cyclophosphamide
  • Chlorambucil
  • Azathioprine
  • Mycophenolate mofetil
  • Cyclosporine

Experimental Treatments

The following treatments have been used for severe disease:

  • Intravenous immune globulin
  • Infliximab
  • Rituximab
  • Total body irradiation
  • Plasma exchange
  • Leukapheresis


There are no known ways to prevent dermatomyositis.


American Academy of Family Physicians

Muscular Dystrophy Association

The Myositis Association

National Institute of Neurological Disorders and Stroke


The Arthritis Society

Muscular Dystrophy Canada


Berkow R, Beers MH, Burs M, eds. The Merck Manual . 17th ed. West Point, PA: Merck & Co; 1999.

Bolognia JL, Jorizzo J, Rapini RP. Dermatology . London: Elsevier Science; 2003.

Chung L, Genovese MC, Fiorentino DF. A pilot trial of rituximab in the treatment of patients with dermatomyositis. Arch Dermatol. 2007;143:763-767.

Dalakas MC. Polymyositis, dermatomyositis, and inclusion body myositis. In: Kasper DL, et al, eds. Harrison's Principles of Internal Medicine . 16th ed. New York: McGraw-Hill; 2005: 2540-2545.

Dermatomyositis. EBSCO Dynamed website. Available at: http://www.ebscohost.com/dynamed/what.php . Accessed August 2005.

Dold S, Justiniano ME, Marquez J, Espinoza LR. Treatment of early and refractory dermatomyositis with infliximab: a report of two cases. Clin Rheumatol. 2007;26:1186-1188.

Wong EH, Hui AC, Griffith JF, et al. MRI in biopsy-negative dermatomyositis. Neurology . 2005;64:750.

Last reviewed February 2008 by Ross Zeltser, MD

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.

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