Dermatomyositis is a rare disease that causes inflammation of the skin and muscles. The inflammation can cause an itchy rash and skin thickening, as well as muscle weakness and pain.

Dermatomyositis is an autoimmune disease, in which the body produces antibodies that attack its own tissues. The disease mainly affects middle-aged women. It is treated with medicines to control inflammation and with physical therapy to help relieve muscle problems.

Some people who have dermatomyositis may get better within a few years. Others may have persistent problems that, in some cases, may affect other organs and become severe.