Polymyositis Disease

Polymyositis is a type of chronic inflammation of the muscles.

Polymyositis (PM) is a type of chronic inflammation of the muscles (inflammatory myopathy) related to dermatomyositis and inclusion body myositis. Its name means "inflammation of many muscles" (poly- + myos- + -itis). The inflammation is predominantly of the endomysium in polymyositis, whereas dermatomyositis is characterized by primarily perimysial inflammation.