Myositis

Myositis is a general description for chronic, progressive inflammation of the muscles. Some types of myositis are associated with skin rashes.

This rare disease can be difficult to diagnose, and the cause is sometimes unknown. Symptoms can appear rapidly or gradually over time. Primary symptoms may include muscle pain and soreness, fatigue, trouble swallowing, and difficulty breathing. In the United States, there are an estimated 1,600 to 3,200 new cases per year and 50,000 to 75,000 people living with myositis. Myositis can affect both children and adults. With the exception of one type of myositis, women are more likely to be affected by this disease than men.

Types of myositis

The five types of myositis are:

• Dermatomyositis
• Inclusion-body myositis
• Juvenile myositis
• Polymyositis
• Toxic myositis

What causes myositis?

Experts differ in their opinions as to the exact cause of myositis. Myositis is thought to be an autoimmune condition that causes the body to attack the muscles. Most cases don’t have a known cause. However, it’s thought that injury and infection may play a role.

Some researchers believe that myositis may also be caused by:

• autoimmune diseases such as rheumatoid arthritis and lupus
• viruses such as the common cold, flu, and HIV
• drug toxicity

How is myositis diagnosed?

TPeople with myositis are often given a misdiagnosis. It can be difficult to diagnose myositis since it’s rare, and also because the primary symptoms are muscle weakness and fatigue. These symptoms are found in many other common diseases.