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Polymyositis (PM) and Dermatomyositis (DM)

Polymyositis and dermatomyositis are inflammatory diseases that cause inflammation of the muscles. Most patients experience the slow onset of muscle weakness over several months. The affected muscles are usually close to the trunk, so people may notice difficulty washing their hair or getting out of a chair. Muscles of the esophagus may be affected, causing difficulty swallowing. If the diaphragm (a large muscle in the thorax) is affected, shortness of breath can occur. Patients with dermatomyositis can develop a rash or other skin changes, often over the eyes and face. PM and DM are rare diseases than affect women more than men.