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 are signs and symptoms of polymyositis and dermatomyositis?

Weakness of muscles is the most common symptom of polymyositis. The muscles involved usually are those that are closest to the trunk of the body. Both sides of the body are affected. The onset can be gradual or rapid. This results in varying degrees of loss of muscle power and atrophy. The loss of strength can be noticed as difficulty getting up from chairs, walking, climbing stairs, or lifting above the shoulders. Trouble with swallowing and weakness lifting the head from the pillow can occur. Occasionally, the muscles ache and are tender to the touch.

Patients can also feel fatigue, a general feeling of discomfort, and have weight loss and/or low-grade fever.

Weakness of the muscles that produce the voice can lead to a weak-sounding voice (dysphonia).

With skin involvement (dermatomyositis), the eyes can be surrounded by a violet discoloration with swelling. There can be scaly reddish discoloration over the knuckles, elbows, and knees (Gottron's sign). There can also be reddish rash on the face, neck, and upper chest. The skin changes can occur with or prior to the development of muscle weakness. Hard lumps of calcium deposits can develop in the fatty layer of the skin, most commonly in childhood dermatomyositis.

Heart and lung involvement can lead to irregular heart rhythm, heart failure, and inflammation of the lungs with shortness of breath.

Because polymyositis can appear in combination with other illnesses (see related articles on systemic lupus erythematosus, scleroderma, and rheumatoid arthritis), it can also have overlap features with them. These illnesses are discussed elsewhere.

Both polymyositis and dermatomyositis can sometimes be associated with cancers, including lymphoma, breast cancer, lung cancer, ovarian cancer, and colon cancer. The cancer risk is reported to be much greater with dermatomyositis than polymyositis.

Medically Reviewed by a Doctor on 5/18/2016

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