Juvenile myositis (JM), including Juvenile Dermatomyositis (JDM) and Juvenile Polymyositis (JPM), is a group of rare and life-threatening autoimmune diseases, in which the body’s immune system attacks its own cells and tissues. Myositis means inflammation of the muscles that you use to move your body. It typically affects children ages 2 to 15 years, with symptoms that include weakness of the muscles close to the trunk of the body, inflammation, edema, muscle pain, fatigue, skin rashes, abdominal pain, fever, and contractures. Children with juvenile dermatomyositis may have difficulty swallowing and breathing, and the heart may also be affected. About 20 to 30 percent of children with juvenile dermatomyositis develop calcium deposits in the soft tissue. Muscle weakness without a rash is the primary symptom of Juvenile Polymyositis. Although medications can help alleviate the symptoms of JM, the disease has no known cure.