Peculiar clinicopathological features of immune-mediated necrotizing myopathiesAllenbach, Yvesa,b; Benveniste, Oliviera,bCurrent Opinion in Rheumatology: November 2018 - Volume 30 - Issue 6 - p 655–663 doi: 10.1097/BOR.0000000000000547 MYOSITIS AND MYOPATHIES: Edited by Andrea Doria and Anna Ghirardello Abstract Author InformationAuthors Article MetricsMetrics Purpose of review In the past decade, immune-mediated necrotizing myopathies have emerged as a separate entity in the heterogenous group of autoimmune myopathies. This group is characterized by clinical manifestations restricted to the muscle tissue, and until recently, the definition was based on muscular pathological features. Recent findings It was shown that they are the most severe autoimmune myopathies in term of muscle damages. They have been associated with two myositis-specific antibodies: either anti-signal recognition particle (anti-SRP) or anti-hydroxy-3-methylglutaryl-CoA reductase (anti-HMGCR) antibodies. These two antibodies are now considered as immune-mediated necrotizing myopathy (IMNM) diagnostic criteria. Each antibody delineates a homogenous subgroup of IMNM patients in terms of severity and IMNM without myositis-specific antibodies have a high risk of malignancy. In addition, pathological observations as well as in-vitro experiments suggest the pathogenic role of anti-SRP and anti-HMGCR antibodies. Summary IMNM are muscle-specific autoimmune diseases associated with a severe weakness and a risk poor muscle strength recovery. Anti-SRP and anti-HMGCR antibodies are specifically associated with this condition and are crucial for the diagnosis and the prognosis. The muscle biopsy remains necessary for IMNM diagnosis in absence of myositis-specific antibodies. aSorbonne Universités, AP-HP, Hôpital Pitié Salpêtrière, Département de médecine Interne et Immunologie Clinique, Centre de Référence Maladies Neuro-Musculaires bINSERM - Centre de Recherche en Myologie - UMRS 974, Paris, France Correspondence to Yves Allenbach, Département de médecine Interne et Immunologie Clinique, Centre de Référence Maladies Neuro-Musculaires, Hôpital Pitié Salpêtrière, 82 boulevard de l’hôpital, F-75013 Paris, France. Tel: +33 1 42 16 10 96; e-mail: Yves.email@example.com Copyright © 2018 Wolters Kluwer Health, Inc. All rights reserved.