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Review
. 2018 Mar 26;20(4):21.
doi: 10.1007/s11926-018-0732-6.

Immune-Mediated Necrotizing Myopathy

Iago Pinal-Fernandez  1   2 , Maria Casal-Dominguez  3   4 , Andrew L Mammen  5   6   7
Affiliations
Review

Immune-Mediated Necrotizing Myopathy

Iago Pinal-Fernandez et al. Curr Rheumatol Rep. .

Abstract

Purpose of review: Immune-mediated necrotizing myopathy (IMNM) is a type of autoimmune myopathy characterized by relatively severe proximal weakness, myofiber necrosis with minimal inflammatory cell infiltrate on muscle biopsy, and infrequent extra-muscular involvement. Here, we will review the characteristics of patients with IMNM.

Recent findings: Anti-signal recognition particle (SRP) and anti-hydroxy-3-methylglutaryl-CoA reductase (HMGCR) autoantibodies are closely associated with IMNM and define unique subtypes of patients. Importantly, the new European Neuromuscular Centre criteria recognize anti-SRP myopathy, anti-HMGCR myopathy, and autoantibody-negative IMNM as three distinct subtypes of IMNM. Anti-SRP myopathy patients have more severe muscle involvement, have more common extra-muscular features, and may respond best to immunosuppressive regimens that include rituximab. In contrast, anti-HMGCR myopathy is often associated with statin exposure and intravenous immunoglobulin treatment may be an effective treatment, even as monotherapy. Both anti-SRP and anti-HMGCR myopathy tend to be most severe in younger patients. Furthermore, children with these forms of IMNM may present with dystrophy-like features which are potentially reversible with immunosuppressant treatment. IMNM patients with either autoantibody may experience fatty replacement of muscle soon after disease onset, suggesting that intense and early immunosuppressant therapy may provide the best chance to avoid long-term disability. IMNM is composed of anti-SRP myopathy, anti-HMGCR myopathy, and autoantibody-negative IMNM. Both anti-SRP and anti-HMGCR myopathy can cause severe weakness, especially in younger patients. Anti-SRP myopathy patients tend to have the most severe weakness and most prevalent extra-muscular features. Autoantibody-negative IMNM remains poorly described.

Keywords: Autoantibodies; HMGCR protein, human; Myositis; Necrotizing myositis; Polymyositis; Signal recognition particle.

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Conflict of interest statement

Conflict of Interest The authors declare that they have no conflict of interest.

Figures

Fig. 1
Fig. 1
Association of creatine kinase (CK) levels with anti-HMGCR titers (a and b) and examples of the evolution of strength and CK over time in a patient with immune-mediated necrotizing myopathy (c and d). Expressing the CK levels in a logarithmic scale (a and c) correlates better with the activity of the disease (autoantibody levels and strength) than when using it in a linear scale (b and d)
Fig. 2
Fig. 2
Examples of T1-weighted (T1W) turbo spin echo (TSE) and short tau inversion recovery (STIR) sequences showing edema (red arrow), atrophy (red arrow head), and fatty replacement (blue arrow) in a patient with immune-mediated necrotizing myositis (IMNM)
Fig. 3
Fig. 3
Representative muscle biopsy of a patient with immune-mediated necrotizing myopathy, showing degenerating fibers (arrow head), myophagocytosis (arrow), and many atrophic fibers
See this image and copyright information in PMC

References

    1. Dalakas MC. Inflammatory muscle diseases. N Engl J Med. 2015;373(4):393–4. - PubMed
    1. Hoogendijk JE, Amato AA, Lecky BR, Choy EH, Lundberg IE, Rose MR, et al. 119th ENMC international workshop: trial design in adult idiopathic inflammatory myopathies, with the exception of inclusion body myositis, 10–12 October 2003, Naarden, The Netherlands. Neuromuscul Disord. 2004;14(5):337–45. - PubMed
    1. Allenbach Y, Mammen AL, Stenzel W, Benveniste O. Immune-mediated necrotizing myopathies working G. 224th ENMC International Workshop:: Clinico-sero-pathological classification of immune-mediated necrotizing myopathies Zandvoort, The Netherlands, 14–16 October 2016. Neuromuscul Disord. 2017 Most recent classification criteria in IMNM. It includes consensus treatment recommendations for the different IMNM subsets. - PubMed
    1. Senecal JL, Raynauld JP, Troyanov Y. Editorial: a new classification of adult autoimmune myositis. Arthritis Rheumatol. 2017;69(5):878–84. - PubMed
    1. Nakao Y, Mukai R, Kabashima T, Ohshima Y, Hamaguchi H, Kashiwagi H, et al. A novel antibody which precipitates 7.5S RNA is isolated from a patient with autoimmune disease. Biochem Biophys Res Commun. 1982;109(4):1332–8. - PubMed