Polymyositis, necrotizing autoimmune myositis, myofasciitis, and overlap-myositis

Marinos C Dalakas MD (

Dr. Dalakas of the National and Kapodistrian University of Athens Medical School in Greece and Thomas Jefferson University, Philadelphia, Pennsylvania, received honorariums from Baxalta (Shire), Novartis, Pfizer, CSL, and Octapharma for consulting, serving on advisory committees, and speaking engagements.

Emma Ciafaloni MD, editor. (

Dr. Ciafaloni of the University of Rochester received personal compensation for serving on advisory boards and/or as a consultant for Avexis, Biogen, Pfizer, PTC Therapeutics, Sarepta, Ra pharma, Wave, and Strongbridge Biopharma; and for serving on a speaker’s bureau for Biogen. Dr Ciafaloni also received research and/or grant support from Orphazyme, PTC Therapeutics, Santhera, and Sarepta.

Originally released March 11, 1994; last updated January 4, 2020; expires January 4, 2023

This article includes discussion of polymyositis, necrotizing autoimmune myositis, myofasciitis, and overlap-myositis, polymyositis, necrotizing autoimmune myositis and fasciitis, and polymyositis and fasciitis. The foregoing terms may include synonyms, similar disorders, variations in usage, and abbreviations.

Historical note and terminology

Although first recorded by Wagner in 1863 (Wagner 1863), polymyositis became a recognized clinical entity 75 years later when Walton and Adams published a remarkable monograph titled Polymyositis (Walton and Adams 1938). These authors defined the term “polymyositis” as an all-inclusive designation of 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." Today, described by neurologists as a neuromuscular disorder, polymyositis is cared for not only by neurologists but also by rheumatologists, who approach the illness as in a setting of other rheumatic diseases. Polymyositis is a rare disorder that, by all accounts, is the most overdiagnosed acquired myopathy. It is discussed in conjunction with 3 similar but more distinct and more frequent entities as evolved in the last decade, namely necrotizing myositis, myofasciitis, and overlap myositis.

The study of polymyositis requires a scholarly review of the neurologic examination, muscle histopathology, immunopathology, and biochemistry to ensure that toxic, metabolic, or mitochondrial muscle diseases are not missed and that 2 more common entities, the inclusion body myositis and the necrotizing autoimmune myositis, are not overlooked (Banker and Engel 1986; Engel and Emslie-Smith 1989; Dalakas 1990; Dalakas 1991; Dalakas 2001a; Dalakas 2001b; 2002; 2010a; 2010b; 2015a; Rowland 1995; Dalakas and Hohlfeld 2003; Mastaglia et al 2003; Dalakas and Karpati 2010; Schmidt and Dalakas 2010).

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