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Causes / Inheritance

What causes dermatomyositis?

In most cases, the cause of the idiopathic inflammatory myopathies (IIMs), the disease group that encompasses dermatomyositis, is unclear. For some reason, the body’s immune system turns against its own tissues in an autoimmune process. In dermatomyositis, the autoimmune process causes inflammation and damage in the blood vessels and connective tissues that supply and support muscles and skin.

A combination of genetic, immune, and environmental factors is thought to contribute to development of the IIMs. Some environmental triggers that have been associated with dermatomyositis include viral infection, certain medications, and sun exposure.


  1. Dalakas MC. Inflammatory Muscle Diseases. Longo DL, ed. N Engl J Med. 2015;372(18):1734-1747. doi:10.1056/NEJMra1402225
  2. Baig S, Paik JJ. Inflammatory muscle disease – An update. Best Pract Res Clin Rheumatol. 2020;34(1):101484. doi:10.1016/j.berh.2019.101484

Last update: Feb 2023
Reviewed by Julie Paik, MD, MHS; Johns Hopkins University

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