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Johns Hopkins Symptoms and Remedies

Johns Hopkins Medicine

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Dermatomyositis

What is it?

Dermatomyositis is a rare connective tissue disease characterized by inflammation of the muscles and skin. As dermatomyositis progresses, muscle tissue is wasted and gradually replaced by scar tissue. Muscle weakness is the primary symptom. Typically affected are the large skeletal muscles (those in the arms, shoulders, pelvis, and thighs), but the heart and the involuntary muscles that control swallowing and breathing may also be involved. Some people develop polymyositis alone, which means that only muscles are affected; in others, the skin (dermis) is involved too, hence the name dermatomyositis. Onset of symptoms may be sudden or gradual. Dermatomyositis is potentially life-threatening when vital organs are affected, but the survival rate has improved in recent years (currently about 75 percent of patients survive beyond six or seven years of diagnosis), and the majority of patients improve with treatment. Two-thirds of those afflicted with dermatomyositis are women.

What Causes It?

  • Dermatomyositis or polymyositis can occur alone (idiopathic) or may be associated with another rheumatic disease, such as systemic lupus erythematosus or Sjögren's syndrome.

Prevention

  • Dermatomyositis cannot be prevented.

Diagnosis

  • Physical examination and patient history are needed.
  • Blood tests are taken to look for enzymatic evidence of muscle inflammation.
  • Electromyography (which measures electrical activity in the muscles) may be performed.
  • A biopsy may be performed to remove a sample of affected muscle tissue for examination under a microscope.

How to Treat It

  • Corticosteroid drugs such as prednisone are usually prescribed (often in high doses) to reduce inflammation.
  • Immunosuppressant drugs may be used if corticosteroids are not effective in relieving inflammation.
  • Physical therapy may be advised to minimize shrinkage of the muscles.

When to Call a Doctor

  • Call a doctor if you develop symptoms of dermatomyositis.