What is dermatomyositis? Dermatomyositis is an inflammatory condition that affects the muscles and is characterized by muscle pain and skin rashes. It may result in chronic inflammation of your muscles and skin, which causes muscle pain, weakness, atrophy (reduction in size), and dysfunction. In addition, a purple or dark red rash may occur anywhere on the skin, but most typically appears on the eyelids and in places on the skin where a muscle covers a joint, such as the elbows, knees, knuckles and toes. The exact cause of dermatomyositis is not clear. It is thought to have a genetic link or possibly be related to a previous infection. It is also similar to autoimmune diseases because the immune system targets the muscle and skin tissues. Studies have shown that people who have dermatomyositis usually have elevated muscle enzymes and elevated autoantibody levels. Dermatomyositis occurs most often in women who are 40 to 60 and in children who are 5 to 15. The disease is less common in men than in women. (Source: PubMed). The symptoms of dermatomyositis typically develop slowly, possibly over weeks or several months. Once you develop dermatomyositis, you may have periods of remission followed by flare-ups of symptoms. The most common symptom of dermatomyositis is a skin rash that is a dark reddish or purple color and appears on your skin in places where muscles are involved in joint movement. Muscle symptoms occur when blood vessels in the muscle fibers become inflamed, causing muscle damage, which results in muscle weakness, atrophy, and pain. Fortunately, the symptoms of dermatomyositis can be treated successfully. The most common treatment is immunosuppressant medications, such as corticosteroids, that will suppress the immune system response and relieve pain. Support therapies include physical therapy to help strengthen affected muscles and speech therapy when muscles involving speech are affected. In some cases, dermatomyositis can be associated with serious conditions or symptoms. Seek immediate medical care (call 911) for serious symptoms, such as profound weakness, inability to urinate, severe muscle pain, difficulty breathing, or chest pain. Seek prompt medical care if you are being treated for dermatomyositis but mild symptoms recur or are persistent.