Polymyositis and Dermatomyositis

  • Medical Author:
    William C. Shiel Jr., MD, FACP, FACR

    Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

  • Medical Editor: Catherine Burt Driver, MD
    Catherine Burt Driver, MD

    Catherine Burt Driver, MD

    Catherine Burt Driver, MD, is board certified in internal medicine and rheumatology by the American Board of Internal Medicine. Dr. Driver is a member of the American College of Rheumatology. She currently is in active practice in the field of rheumatology in Mission Viejo, Calif., where she is a partner in Mission Internal Medical Group.

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What types of doctors treat polymyositis and dermatomyositis?

Polymyositis is typically treated by rheumatologists. Others who can be involved in the care of patients with polymyositis include internists, pathologists, dermatologists, radiologists, cardiologists, neurologists, surgeons, and physiatrists.

What is the treatment for polymyositis and dermatomyositis?

Initially, polymyositis is treated with high doses of corticosteroids. Corticosteroids are cortisone medications (such as prednisone and prednisolone). These are medications related to cortisone and can be given by mouth or intravenously. They are given because they can have a powerful effect to decrease the inflammation in the muscles. They usually are required for years, and their continued use will be based on what the doctor finds related to symptoms, examination, and muscle enzyme blood test.

Corticosteroids have many predictable and unpredictable side effects. In high doses, they commonly cause an increase in appetite and weight, puffiness of the face, and easy bruising. They can also cause sweats, facial-hair growth, upset stomach, sensitive emotions, leg swelling, acne, cataracts, osteoporosis, high blood pressure, worsening of diabetes, and increased risk of infection. A rare complication of cortisone medications is severe bone damage (avascular necrosis) which can destroy large joints, such as the hips and shoulders. Further, abruptly stopping corticosteroids can cause flares of the disease and result in other side effects, including nausea, vomiting, and decreased blood pressure.

Corticosteroids do not always adequately improve polymyositis. In these patients, immunosuppressive medications are considered. These medications can be effective by suppressing the immune response that attracts the white blood cells of inflammation to the muscles. Many types are now commonly used and others are still experimental. Methotrexate (Rheumatrex, Trexall) can be taken by mouth or by injection into the body. Azathioprine (Imuran) is an oral drug. Both can cause liver and bone-marrow side effects and require regular blood monitoring. Cyclophosphamide (Cytoxan), chlorambucil (Leukeran), and cyclosporine (Sandimmune) have been used for serious complications of severe disease, such as scarring of the lungs (pulmonary fibrosis). These also can have severe side effects which must be considered with each patient individually. Treatment with intravenous infusion of immunoglobulins (IVIG) has been shown to be effective in severe cases of polymyositis that are resistant to other treatments. Recent research reports indicate that intravenous rituximab (Rituxan) may be helpful in treating resistant disease.

Patients with calcium deposits (calcinosis) from dermatomyositis can sometimes benefit by taking diltiazem (Cardizem) to shrink the size of the calcium deposits. This effect, however, occurs slowly (frequently over years) and is not always effective. The complication of calcium deposits in muscles and soft tissues occurs more frequently in children than adults.

Physical therapy with gradual muscle strengthening is an important part of the treatment of polymyositis. When to begin and the continued degree of exercise and range of motion of extremities is customized for each patient.

Patients can ultimately do well, especially with early medical treatment of disease and disease flares. The disease frequently becomes inactive, and rehabilitation of atrophied muscle becomes a long-term project. Monitoring for signs of cancer, heart, and lung disease are essential. Accordingly, EKG, lung function testing, and X-ray tests are used.

As mentioned above, the related muscle disease called inclusion body myositis is often more resistant to treatment than polymyositis. As scientists better define the specific causes of the different forms of polymyositis, treatment will be more accurately aimed at cure of this disease. Researchers are finding more specific antibodies in patients that may be used to diagnose and define active disease.

Medically Reviewed by a Doctor on 5/18/2016

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