The exact cause is not known. It may be due to a problem with the immune system that causes it to attack healthy tissue. Genes and the environment may also play a role.

Risk Factors

This problem is more common in women. It often starts in people who are 30 to 50 years old.

Other things that may raise the risk are:

Symptoms

Problems may be:

A purple-red, itchy rash that may appear on the face, neck, trunk, fingers, or around joints
Skin that is sensitive to sunlight
Muscle weakness in the shoulder and hips
Swelling of the skin
Muscle pain
Problems swallowing
Swollen blood vessels

Diagnosis

You will be asked about your symptoms and health history. A physical exam will be done. You may be referred to a specialist for further evaluation.

Your bodily fluids and tissues may be tested. This can be done with:

Blood tests
Skin or muscle biopsy

Images may be taken of structures in the body. This can be done with:

MRI scan or ultrasound
CT scan

Muscles may be tested. This can be done with an electromyogram (EMG).

Lung function may be tested. This can be done with a pulmonary function test.

Skin Biopsy

Treatment

There is no cure. The goal of treatment is to manage symptoms and improve quality of life. Choices are:

Physical therapy to improve muscle strength and flexibility
Medicines to suppress the immune system, such as corticosteroids
Lifestyle changes, such as exercising regularly and using sun protection

People with severe symptoms may be given immune globulin by IV. It contains antibodies that can block the unhealthy ones linked to dermatomyositis.

Prevention

There are no known guidelines to prevent this health problem.

RESOURCES:

The Myositis Association
http://www.myositis.org

National Institute of Neurological Disorders and Stroke
https://www.ninds.nih.gov

CANADIAN RESOURCES:

The Arthritis Society
http://www.arthritis.ca

Muscular Dystrophy Canada
http://www.muscle.ca

References:

Dermatomyositis. National Institute of Neurological Disorders and Stroke website. Available at: https://www.ninds.nih.gov/Disorders/All-Disorders/Dermatomyositis-Information-Page. Accessed October 23, 2020.

Dermatomyositis. EBSCO Dynamed website. Available at: https://www.dynamed.com/condition/dermatomyositis. Accessed October 23, 2020.

Ernste FC, Reed AM. Idiopathic inflammatory myopathies: current trends in pathogenesis, clinical features, and up-to-date treatment recommendations. Mayo Clin Proc. 2013 Jan;88(1):83-105.

Last reviewed September 2020 by EBSCO Medical Review Board Daniel A. Ostrovsky, MD
Last Updated: 5/18/2021

EBSCO Information Services is fully accredited by URAC. URAC is an independent, nonprofit health care accrediting organization dedicated to promoting health care quality through accreditation, certification and commendation.

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.

To send comments or feedback to our Editorial Team regarding the content please email us at healthlibrarysupport@ebsco.com. Our Health Library Support team will respond to your email request within 2 business days.