The typical characteristic of dermatomyositis is a skin rash (caused by skin inflammation) that precedes or accompanies progressive muscle weakness caused by muscle inflammation. Dermatomyositis may be associated with collagen-vascular or autoimmune diseases, such as lupus.

Dermatomyositis can affect any age group, but is more likely to occur in middle-aged adults. In children, it usually appears between the ages of 5 and 15. It is twice as common in women.

The cause of dermatomyositis is unknown. It may be related to an autoimmune reaction, or may be triggered by a virus or cancer.

Symptoms

  • greyish-red rash; (see below);
  • gradual muscle weakness – upper arms, neck, and legs on both sides of the body;
  • joint pain;
  • fever;
  • weight loss;
  • fatigue;
  • some have difficulty swallowing;
  • as the disease progresses, the muscles begin to waste away (atrophy) and permanently shorten (contracture);
  • children with juvenile dermatomyositis may experience a more rapid onset.

A greyish-red rash appears at the same time as the muscle weakness. The rash commonly appears on the face and includes a purplish swelling, called a heliotrope, around the eyes. There may be a shawl-like rash over the neck, shoulders, and upper chest and back. Another rash often appears around the joints, especially around the fingers. This rash may be smooth or may have scaly patches and is called Gottron’s sign. When the rash fades, it leaves behind pigmented patches of skin.

Some people with dermatomyositis develop a rash without muscle weakness. This is called dermatomyositis sine myositis. Others may also have Raynaud’s phenomenon, in which the small arteries in the fingers and toes constrict, causing the skin to look pale or bluish, usually after exposure to cold.

People with dermatomyositis are more likely to develop malignant cancers.

 

How is it diagnosed?

Dermatomyositis is diagnosed through a variety of tests including:

  • Physical examination – especially for characteristic symptoms;
  • Blood tests – to check for higher than normal creative phosphokinase (CK) enzyme, suggesting muscle damage and particular autoantibodies;
  • Muscle biopsy – to check for abnormalities;
  • Electromyography – wires attached to the skin measure muscle activity;
  • Magnetic Resonance Imaging (MRI) is helpful to reveal muscle inflammation;
  • Cancer screening tests.

Treatment options

There is no cure for dermatomyositis, but the symptoms can be treated.  Options include medication, physical therapy, exercise, heat therapy (including microwave and ultrasound), orthotics, and assistive devices as well as rest.

  • Corticosteroid drug, given either in pill form or intravenously;
  • Immunosuppressant drugs, such as azathioprine and methotrexate;
  • Periodic treatment using intravenous immunoglobulin (IVIG) can also improve recovery;
  • Other immunosuppressive agents include cyclosporine A, cyclophosphamide, and tacrolimus;
  • Physical therapy is usually recommended to prevent muscle atrophy and to regain muscle strength and range of motion;
  • A topical ointment, such as topical corticosteroids, for skin inflammation.

Patients should wear a high-protection sunscreen and protective clothing.  Surgery may be required to remove calcium deposits that cause nerve pain and recurrent infections.

Self-care tips

While there is no known way to prevent dermatomyositis, you can find relief from symptoms and possible remission by following your doctor’s treatment recommendations. It is very important to reduce your physical activity until your muscles have had the opportunity to recover.

 

  • This information sheet is not a substitute for medical advice.

Copyright: Muscular Dystrophy Australia
www.mda.org.au

Authorisation has been provided to
The Myositis Association-Australia Incorporated
to reproduce this information sheet.