A muscle biopsy showing muscle fiber necrosis with little to no inflammation should raise the possibility of a necrotizing autoimmune myopathy that is somewhat resistant to corticosteroid monotherapy.
When considering the treatable autoimmune myopathies, we usually think of the inflammatory myopathies, best characterized by polymyositis and dermatomyositis. There is, however, a group of immune-mediated myopathies that is characterized more by muscle fiber necrosis than by inflammation: the necrotizing autoimmune myopathies (NAMs). These too are treatable, but probably in a way that differs somewhat from how we treat the inflammatory myopathies. Recognized associations with the NAMs include underlying malignancy, connective tissue diseases, and autoantibodies against signal recognition peptide (SRP) and 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR; the rate-limiting enzyme in cholesterol biosynthesis that is inhibited by statins). Desp…
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DisclosuresGrant / Research supportNIH NeuroBioBank; ALS Association; NIH/National Institute of Neurological Disorders and Stroke; NIH/National Center for Advancing Translational Sciences; FDA; Department of Defense
Editorial boardsCochrane Collaboration
Leadership positions in professional societiesMuscle Study Group Executive Committee
DisclosuresGrant / Research supportNIH NeuroBioBank; ALS Association; NIH/National Institute of Neurological Disorders and Stroke; NIH/National Center for Advancing Translational Sciences; FDA; Department of Defense
Editorial boardsCochrane Collaboration
Leadership positions in professional societiesMuscle Study Group Executive Committee