Myositis

Myositis means muscle inflammation. There are various forms of myositis. One form is polymyositis, which affects muscles throughout the body. Another is dermatomyositis, which affects both muscle and skin. Other body tissues can be affected as well. There are forms of myositis that are linked to inflammation in the lung.

Myositis is thought to be an immune system problem. Immune cells in the body are designed to attack and destroy invading viruses and harmful bacteria. In myositis, the immune system attacks the body's own tissues. Health experts don't know why this happens. Skin, muscle tissue, or both are often involved. Other parts of the body may also be affected. This includes the lungs. Myositis may be triggered by exposure to certain chemicals, medicines, or viruses. But often a cause can't be found. This is known as idiopathic myositis.

The main symptom of myositis is muscle weakness or aching (especially large muscles such as those on the thighs, hips, shoulders, neck, and trunk). This can make it hard to climb stairs, get out of chairs, lift heavy things, or raise arms overhead. The muscles in the throat can also be affected. This can lead to trouble swallowing. People with dermatomyositis often have skin changes. This may include a rash. Children may have different symptoms from adults.

People with myositis should be assessed for lung disease.

Some people have only mild symptoms that get better with treatment. But in many cases the disease is long-lasting (chronic). There are times when symptoms are worse (active disease). These may be followed by times when symptoms get better or go away (remission).

Treatment may include steroid medicines taken by mouth (oral). It may also include medicines that suppress the immune system. Rest, physical therapy, and exercise may help ease symptoms.