(Idiopathic Inflammatory Myopathy)
The exact cause of dermatomyositis is not known. It may be an autoimmune disorder. The immune system identifies and attacks viruses and harmful bacteria in your body. An autoimmune disorder means the immune system begins to attack normal healthy tissue.
A viral infection may trigger dermatomyositis.
Your chance of developing dermatomyositis is higher if you have a connective tissue disorder such as:
Dermatomyositis is also associated with certain genes.
Dermatomyositis may cause:
Your doctor will ask about your symptoms and medical 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:
Your muscles may be tested. This can be done with electromyogram (EMG).
Images may be taken of your bodily structures. This can be done with:
There is no cure for dermatomyositis. Treatment is focused on managing the symptoms. Talk with your doctor about the best treatment plan for you. Treatment options include the following:
You may be referred to a physical therapist. The therapist will help improve or prevent the loss of muscle strength and function. It may include:
Corticosteroids can suppress your immune system. This will decrease inflammation in the muscle. Steroid medication can also be used on the skin to relieve skin symptoms. Corticosteroids can cause problems, like lower bone density. They can also increase infections. To lower these effects, you will be given the lowest dose needed to control your symptoms. You may also be asked to take supplements like calcium and vitamin D to improve your bone strength.
There are other medication options that can help to suppress the immune system. They may be used with or instead of the corticosteroids.
Intravenous Immune Globulin
Immune globulin has healthy antibodies from several donors. These antibodies can block the unhealthy antibodies associated with dermatomyositis. It is given through an IV.
The infusion needs to be repeated every few weeks.
Regular exercise can help you develop and maintain muscle strength. Modify the program as needed to prevent irritating your condition. Check with your doctor and physical therapist for exercise guidelines. Rest when needed.
Your skin may also be more sensitive to the sun. Use sunscreen or cover your skin with clothes or a hat.
The Myositis Association
National Institute of Neurological Disorders and Stroke
The Arthritis Society
Muscular Dystrophy Canada
Chung L, Genovese MC, et al. A pilot trial of rituximab in the treatment of patients with dermatomyositis. Arch Dermatol. 2007;143:763-767.
Dermatomyositis. National Institute of Neurological Disorders and Stroke website. Available at: http://www.ninds.n.... Updated August 26, 2011. Accessed August 7, 2013.
Idiopathic inflammatory myopathy. EBSCO Dynamed website. Available at: http://www.ebscohost.com/dynamed/what.php. Updated April 7, 2013. Accessed August 7, 2013.
Dold S, Justiniano ME, et al. Treatment of early and refractory dermatomyositis with infliximab: a report of two cases. Clin Rheumatol. 2007;26:1186-1188.
Wong EH, Hui AC, et al. MRI in biopsy-negative dermatomyositis. Neurology. 2005;64:750.
Last reviewed August 2013 by Michael Woods, MD