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Dermatomyositis

Definition

Dermatomyositis is connective-tissue disease that is characterized by inflammation of the muscles and the skin.

Causes, incidence, and risk factors

The cause of this disorder is unknown. It is theorized that an autoimmune reaction or a viral infection of the skeletal muscle may cause the disease. It can affect people at any age, but most commonly occurs in people 40 - 60 years old, or in children from 5 - 15 years old.

It affects women much more often than men. Muscle weakness may appear suddenly or occur slowly over weeks or months. There may be difficulty with raising the arms over the head, rising from a sitting position, and climbing stairs.

A dusky, purplish red rash may appear over the face, neck, shoulders, upper chest, and back. Joint pain, inflammation of the heart, and lung (pulmonary) disease may occur.

A malignancy may sometimes be associated with this disorder. A similar condition is called polymyositis when the symptoms occur without any skin manifestations.

Symptoms

Muscles weak, stiff or sore
Butterfly rash
Upper eyelids purple/violet colored
Muscle weakness
Red, dusky skin rash
Difficulty swallowing
Shortness of breath
Skin redness or inflammation

Signs and tests

During a physical examination, the doctor will identify muscle weakness and the typical rash.

Tests may include:

Electromyography, showing inflammation in muscles
Magnetic resonance imaging (MRI)
A muscle biopsy
An elevated serum creatine phosphokinase
An elevated serum aldolase
ECG

Treatment

The disease is treated with corticosteroid medications or other immunosuppressive drugs. When an improvement of muscle strength is achieved, the medication is slowly tapered. Maintenance therapy with prednisone is often continued indefinitely.

If the condition is associated with a tumor, the condition may improve if the tumor is removed.

Expectations (prognosis)

Remissions and recovery have been reported, especially in children. In adults, death may result from severe and prolonged muscle weakness, malnutrition, pneumonia, or respiratory failure. The outcome is usually worse if cardiac or pulmonary involvement is present.

Complications