Literally meaning: "inflammation of several or many muscles at once"
Origin: Anc Greek
+μυο-/myo-(=combining form meaning muscle) > μυς/mys/ (=muscle) > μύω/myo(=enclosed like the muscle inside body or rat in its nest=epimys)
+(-ίτιδα)/-itida (=-itis, suffix meaning “pertaining to” or “inflammation”.) It is in feminine gender because it was used with feminine noun η νόσος/ e nosos /(=disease)
Polyomyitis first described by German pathologist Ernst Leberecht Wagner in in 1863. Seventy five years(1938) later Walton and Adams published a monograph titled Polymyositis reffering to polymyositis” as a group of myopathies characterized by a single basic disease process related to "other collagen" diseases or arising as the result of "hypersensitivity response to allergic inflammation."
Polymyositis is a type of chronic inflammatory disease of skeletal muscle disease (myopathy) of unknown etiology that is related to dermatomyositis and inclusion body myositis