What is dermatomyositis?

When the inflammatory muscle disease polymyositis affects the skin, it is called dermatomyositis. In this condition, the eyes can be surrounded by a violet discoloration with swelling. There may be scaly, red skin over the knuckles, elbows, and knees. In addition, a red rash can occur on the face, neck, and upper chest. Hard lumps of calcium deposits can develop in the fatty layer of the skin.

What causes dermatomyositis?

In people with polymyositis and dermatomyositis, the body’s immune system stops working well and begins attacking healthy tissues. Factors triggering this process are not known.

What are the symptoms of dermatomyositis?

Symptoms of dermatomyositis can vary a great deal from patient to patient. Some people may have the disease for months or years before seeing it. Muscle weakness may arise at the same time as the rash, or it may occur weeks, months, or years later. Some other common symptoms include:

  • Reddish or bluish-purple patches, mostly on areas exposed to the sun.
  • Purple spots on bony prominences, especially the knuckles.
  • Discoloration with swelling around the eyes.
  • Ragged cuticles and prominent blood vessels on nail folds.
  • A red rash on the face, neck, shoulders, upper chest and elbows.

Last reviewed by a Cleveland Clinic medical professional on 04/02/2019.


  • Hellmann DB, Imboden JB, Jr.. Rheumatologic & Immunologic Disorders. In: Papadakis MA, McPhee SJ, Rabow MW. eds. Current Medical Diagnosis & Treatment 2015. New York, NY: McGraw-Hill; 2014.
  • Usatine RP, Smith MA, Chumley HS, Mayeaux EJ, Jr. Chapter 181. Dermatomyositis. In: Usatine RP, Smith MA, Chumley HS, Mayeaux EJ, Jr. eds. The Color Atlas of Family Medicine, 2e. New York, NY: McGraw-Hill; 2013.
  • Genetic and Rare Diseases Information Center. Dermatomyositis. Accessed 4/3/2019.
  • American Osteopathic College of Dermatologists. Dermatomyositis. Accessed 4/3/2019.

Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy