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Dermatomyositis is part of a group of rare diseases called the inflammatory myopathies that involve chronic (long-standing) muscle inflammation, muscle weakness, and in some cases, muscle pain. Myopathy is a general term used to describe a number of conditions affecting the muscles. All myopathies can cause muscle weakness. Both children and adults can be affected.

Dermatomyositis is characterized by a skin rash that precedes or accompanies progressive muscle weakness. The rash appears patchy, with purple or red discolorations, and characteristically develops on the eyelids and on muscles used to extend or straighten joints, including knuckles, elbows, knees, and toes. Red rashes also may occur on the:

  • Face
  • Neck
  • Shoulders
  • Upper chest
  • Back, and other locations

There may be swelling in the affected areas. The rash sometimes occurs without obvious muscle involvement and often becomes more evident with sun exposure.

Adults with dermatomyositis may experience weight loss or a low-grade fever, have inflamed lungs, and be sensitive to light. Children and adults with dermatomyositis may develop calcium deposits, which appear as hard bumps under the skin or in the muscle (calcinosis). Calcinosis most often occurs one to three years after disease onset but may occur many years later. These deposits are seen more often in childhood dermatomyositis than in dermatomyositis that begins in adulthood.

In some cases of dermatomyositis, the distal muscles (muscles in the forearms and around the ankles and wrists) may be affected as the disease progresses. The disorder also may be associated with collagen-vascular or autoimmune diseases such as lupus (in which the body's immune response system that normally defends against infection and disease attacks its own muscle fibers, blood vessels, connective tissue, organs, or joints).

How can I or my loved one help improve care for people with dermatomyositis?

Consider participating in a clinical trial so clinicians and scientists can learn more about dermatomyositis and related disorders. Clinical research uses human volunteers to help researchers learn more about a disorder and perhaps find better ways to safely detect, treat, or prevent disease.

All types of volunteers are needed—those who are healthy or may have an illness or disease—of all different ages, sexes, races, and ethnicities to ensure that study results apply to as many people as possible, and that treatments will be safe and effective for everyone who will use them.

For information about participating in clinical research visit NIH Clinical Research Trials and You. Learn about clinical trials currently looking for people with dermatomyositis at

Where can I find more information about dermatomyositis?

The following organizations offer resources about myopathy and muscle diseases:

American Autoimmune Related Diseases Association
Phone: 586-776-3900 or 800-598-4668

Muscular Dystrophy Association
Phone: 800-572-1717

Myositis Association
Phone: 703-299-4850; 800-821-7356

Content source: Accessed July 12, 2023.

The information in this document is for general educational purposes only. It is not intended to substitute for personalized professional advice. Although the information was obtained from sources believed to be reliable, MedLink, its representatives, and the providers of the information do not guarantee its accuracy and disclaim responsibility for adverse consequences resulting from its use. For further information, consult a physician and the organization referred to herein.

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