Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Classification of myositis

Key Points

  • The clinical spectrum of idiopathic inflammatory myopathies (IIMs) has evolved from diseases in which muscle weakness was the main manifestation to systemic inflammatory diseases with multiple organ involvement.

  • The EULAR–ACR classification criteria for adult and juvenile IIMs and their major subgroups capture patients with the typical skin rash of dermatomyositis without muscle weakness (amyopathic dermatomyositis).

  • The myositis-specific autoantibodies (MSAs) are helpful in supporting the diagnosis, classification and subclassification of IIMs, but muscle biopsies with histopathological and immunohistochemical evaluation are still important in many cases to rule out other myopathies.

  • Inclusion body myositis is suggested to be classified on the basis of three features: finger flexor or quadriceps weakness, endomysial inflammation, and invasion of non-necrotic muscle fibres or the presence of rimmed vacuoles.

  • Immune-mediated necrotizing myopathy is characterized by the presence of necrotic muscle fibres, often with scarce or no inflammatory cell infiltrates, typically together with the presence of specific MSAs.

  • Antisynthetase syndrome is characterized by the presence of myositis, interstitial lung disease, mechanic's hand, arthritis and Raynaud phenomenon (albeit some of these features might predominate) together with an antisynthetase antibody.


The idiopathic inflammatory myopathies (IIMs; also known as myositis) are a heterogeneous group of disorders in which a common feature is chronic inflammation of skeletal muscle, leading to muscle weakness. Other organs are frequently affected in IIMs, such as the skin, joints, lungs, gastrointestinal tract and heart, contributing to morbidity and mortality. Currently, IIMs are most often subclassified into polymyositis, dermatomyositis and inclusion body myositis, but this subclassification has limitations as these subgroups often have overlapping clinical and histopathological features, and outcomes vary within the subgroups; additionally, subgroups without considerable myopathy are not included. A new way of subgrouping patients could be on the basis of the presence of myositis-specific autoantibodies. These autoantibodies are associated with distinct clinical features and, moreover, can help to identify subsets of IIMs in which extramuscular symptoms, such as skin manifestations, arthritis or interstitial lung disease, might be the presenting or predominant feature when muscle symptoms are mild or absent. The recognition that subphenotypes with single-organ involvement other than muscles exist is important for identifying patients with early disease, for clinical care demanding team management and in designing clinical studies to improve our understanding of this heterogeneous disease to develop new therapies.

This is a preview of subscription content

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1: Development of classification and diagnostic criteria for idiopathic inflammatory myopathies over time.
Figure 2: Clinical and histological features of the skin in dermatomyositis and conditions that mimic dermatomyositis.
Figure 3: Muscle biopsy findings of patients with two different idiopathic inflammatory myopathies.


  1. 1

    Dalakas, M. & Hohlfeld, R. Polymyositis and dermatomyositis. Lancet 362, 971–982 (2003).

    CAS  Article  Google Scholar 

  2. 2

    Hoogendijk, J. E. 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. 14, 337–345 (2004).

    Article  Google Scholar 

  3. 3

    Euwer, R. & Sontheimer, R. Amyopathic dermatomyositis (dermatomyositis sine myositis). Presentation of six new cases and review of the literature. J. Am. Acad. Dermatol. 24, 959 (1991).

    CAS  Article  Google Scholar 

  4. 4

    Love, L. A. et al. A new approach to the classification of idiopathic inflammatory myopathy: myositis-specific autoantibodies define useful homogeneous patient groups. Medicine 70, 360–374 (1991).

    CAS  Article  Google Scholar 

  5. 5

    Lundberg, I. E., Miller, F. W., Tjärnlund, A. & Bottai, M. Diagnosis and classification of idiopathic inflammatory myopathies. J. Intern. Med. 280, 39–51 (2016).

    CAS  Article  Google Scholar 

  6. 6

    Lundberg, I. E. et al. 2017 European League Against Rheumatism/American College of Rheumatology classification criteria for adult and juvenile idiopathic inflammatory myopathies and their major subgroups. Ann. Rheum. Dis. 76, 1955–1964 (2017).

    Article  Google Scholar 

  7. 7

    Lundberg, I. E. et al. 2017 European League Against Rheumatism/American College of Rheumatology Classification Criteria for Adult and Juvenile Idiopathic Inflammatory Myopathies and Their Major Subgroups. Arthritis Rheumatol. 69, 2271–2282 (2017).

    Article  Google Scholar 

  8. 8

    Medsger, T. A. Jr, Dawson, W. N. Jr & Masi, A. T. The epidemiology of polymyositis. Am. J. Med. 48, 715–723 (1970).

    Article  Google Scholar 

  9. 9

    DeVere, R. & Bradley, W. G. Polymyositis: its presentation, morbidity and mortality. Brain 98, 637–666 (1975).

    CAS  Article  Google Scholar 

  10. 10

    Bohan, A. & Peter, J. B. Polymyositis and dermatomyositis (first of two parts). N. Engl. J. Med. 292, 344–347 (1975).

    CAS  Article  Google Scholar 

  11. 11

    Bohan, A. & Peter, J. B. Polymyositis and dermatomyositis (second of two parts). N. Engl. J. Med. 292, 403–407 (1975).

    CAS  Article  Google Scholar 

  12. 12

    Bohan, A. & Peter, J. B. Bowman, R. L. & Pearson, C. M. Computer-assisted analysis of 153 patients with polymyositis and dermatomyositis. Medicine 56, 255–286 (1977).

    CAS  Article  Google Scholar 

  13. 13

    Tanimoto, K. et al. Classification criteria for polymyositis and dermatomyositis. J Rheumatol. 22, 668–674 (1995).

    CAS  PubMed  Google Scholar 

  14. 14

    Targoff, I. N. et al. Classification criteria for the idiopathic inflammatory myopathies. Curr. Opin. Rheumatol. 9, 527–535 (1997).

    CAS  Article  Google Scholar 

  15. 15

    Troyanov, Y. et al. Novel classification of idiopathic inflammatory myopathies based on overlap syndrome features and autoantibodies: analysis of 100 French Canadian patients. Medicine 84, 231–249 (2005).

    Article  Google Scholar 

  16. 16

    Moghadam-Kia, S., Oddis, C. V., Sato, S., Kuwana, M. & Aggarwal, R. Antimelanoma differentiation-associated gene 5 antibody: expanding the clinical spectrum in North American patients with dermatomyositis. J. Rheumatol. 44, 319–325 (2017).

    CAS  Article  Google Scholar 

  17. 17

    Trallero-Araguás, E. et al. Clinical manifestations and long-term outcome of anti-Jo1 antisynthetase patients in a large cohort of Spanish patients from the GEAS-IIM group. Semin. Arthritis Rheum. 46, 225–231 (2016).

    Article  Google Scholar 

  18. 18

    Betteridge, Z. & McHugh, N. Myositis-specific autoantibodies: an important tool to support diagnosis of myositis. J. Intern. Med. 280, 8–23 (2016).

    CAS  Article  Google Scholar 

  19. 19

    McHugh, N.J. & Tansley, S.L. Autoantibodies in myositis Nat. Rev. Rheumatol. (2018).

  20. 20

    Machado, P. M. et al. Ongoing developments in sporadic inclusion body myositis. Curr. Rheumatol. Rep. 16, 477 (2014).

    Article  Google Scholar 

  21. 21

    Pearson, C. M. in Arthritis (and Allied Conditions) (ed. McCarty, D. J.) 742–761 (Lea & Febiger, Philadelphia, 1979).

    Google Scholar 

  22. 22

    Euwer, R. & Sontheimer, R. D. Amyopathic dermatomyositis: a review. J. Invest. Dermatol. 100, 124S–127S (1993)

    CAS  Article  Google Scholar 

  23. 23

    Gerami, P., Schope, J. M., McDonald, L., Walling, H. W. & Sontheimer, R. D. A systematic review of adult-onset clinically amyopathic dermatomyositis (dermatomyositis siné myositis): a missing link within the spectrum of the idiopathic inflammatory myopathies. J. Am. Acad. Dermatol. 54, 597–613 (2006)..

    Article  Google Scholar 

  24. 24

    Hsiung, S. H. et al. Multicentric reticulohistiocytosis presenting with clinical features of dermatomyositis. J. Am. Acad. Dermatol. 48 (Suppl. 2). S11–S14 (2003).

    Article  Google Scholar 

  25. 25

    Hamaguchi, Y. et al. Clinical correlations with dermatomyositis-specific autoantibodies in adult Japanese patients with dermatomyositis: a multicenter cross-sectional study. Arch. Dermatol. 147, 391–398 (2011).

    CAS  Article  Google Scholar 

  26. 26

    Fiorentino, D., Chung, L., Zwerner, J., Roen, A. & Casciola-Rosen, L. The mucocutaneous and systemic phenotype in dermatomyositis patients with antibodies to MDA5 (CADM-140): a retrospective study. J. Am. Acad. Dermatol. 65, 25–34 (2012).

    Article  Google Scholar 

  27. 27

    Muro, Y. et al. Cutaneous manifestations in dermatomyositis: key clinical and serological features — a comprehensive review. Clin. Rev. Allergy Immunol. 51, 293–302 (2016).

    Article  Google Scholar 

  28. 28

    Mukae, H. et al. Clinical differences between interstitial lung disease associated with clinically amyopathic dermatomyositis and classic dermatomyositis. Chest 136, 1341–1347 (2009).

    Article  Google Scholar 

  29. 29

    Ang, C. C. et al. Clinical signs associated with an increased risk of interstitial lung disease: a retrospective study of 101 patients with dermatomyositis. Br. J. Dermatol. 176, 231–233 (2017).

    CAS  Article  Google Scholar 

  30. 30

    Fiorentino, D. F. et al. Distinctive cutaneous and systemic features associated with antitranscriptional intermediary factor-1gamma antibodies in adults with dermatomyositis. J. Am. Acad. Dermatol. 72, 449–455 (2015).

    Article  Google Scholar 

  31. 31

    Fiorentino, D. & Casciola-Rosen, L. Autoantibodies to transcription intermediary factor 1 in dermatomyositis shed insight into the cancer-myositis connection. Arthritis Rheum. 64, 346–349 (2012).

    Article  Google Scholar 

  32. 32

    Rogers, A., Chung, L., Li. S., Casciola-Rosen, L. & Fiorentino, D. F. The cutaneous and systemic findings associated with nuclear matrix protein-2 antibodies in adult dermatomyositis patients. Arthritis Care Res. 69, 1909–1914 (2017).

    CAS  Article  Google Scholar 

  33. 33

    Fujimoto, M., Watanabe, R., Ishitsuka, Y. & Okiyama, N. Recent advances in dermatomyositis-specific autoantibodies. Curr. Opin. Rheumatol. 28, 636–644 (2016).

    CAS  Article  Google Scholar 

  34. 34

    Klein, R. Q. et al. Comparison of the reliability and validity of outcome instruments for cutaneous dermatomyositis. Br. J. Dermatol. 159, 887–894 (2008).

    CAS  Article  Google Scholar 

  35. 35

    Anyanwu, C. O. et al. Validation of the cutaneous dermatomyositis disease area and severity index: characterizing disease severity and assessing responsiveness to clinical change. Br. J. Dermatol. 173, 969–974 (2015).

    CAS  Article  Google Scholar 

  36. 36

    Tiao, J. et al. Evaluation of the reliability of the cutaneous dermatomyositis disease area and severity index and the cutaneous assessment tool-binary method in juvenile dermatomyositis among paediatric dermatologists, rheumatologists and neurologists. Br. J. Dermatol. 177, 1086–1092 (2017).

    CAS  Article  Google Scholar 

  37. 37

    Tiao, J. et al. The reliability of the cutaneous dermatomyositis disease area and severity index (CDASI) among dermatologists, rheumatologists and neurologists. Br. J. Dermatol. 176, 423–430 (2017).

    CAS  Article  Google Scholar 

  38. 38

    Robinson, E. S., Feng, R., Okawa, J. & Werth, V. P. Improvement in the cutaneous disease activity of patients with dermatomyositis is associated with a better quality of life. Br. J. Dermatol. 172, 169–174 (2015).

    CAS  Article  Google Scholar 

  39. 39

    Yassaee, M., et al. Modification of the cutaneous dermatomyositis disease area and severity index, an outcome instrument. Br. J. Dermatol. 162, 669–673 (2010).

    CAS  Article  Google Scholar 

  40. 40

    Goreshi, R. et al. Evaluation of reliability, validity, and responsiveness of the CDASI and the CAT-BM. J. Invest. Dermatol. 132, 1117–1124 (2012).

    CAS  Article  Google Scholar 

  41. 41

    Huard, C. et al. Correlation of cutaneous disease activity with type 1 interferon gene signature and interferon beta in dermatomyositis. Br. J. Dermatol. 176, 1224–1230 (2017).

    CAS  Article  Google Scholar 

  42. 42

    Werth, V. P. et al. A phase 2 study of safety and efficacy o anabasum (JBT-101), a cannabinoid receptor type 2 agonist, in refractory skin-predominant dermatomyositis [abstract]. Arthritis Rheum. 69 (Suppl.), 7L (2017).

    Google Scholar 

  43. 43

    Engel, A. G. &Arahata, K. Monoclonal antibody analysis of mononuclear cells in myopathies. II: phenotypes of autoinvasive cells in polymyositis and inclusion body myositis. Ann. Neurol. 16, 209–215 (1984).

    CAS  Article  Google Scholar 

  44. 44

    Emslie-Smith, A. M. & Engel, A. G. Microvascular changes in early and advanced dermatomyositis: a quantitative study. Ann. Neurol. 27, 343–356 (1990).

    CAS  Article  Google Scholar 

  45. 45

    Griggs, R. C., et al. Inclusion body myositis and myopathies. Ann. Neurol. 38, 705–713 (1995).

    CAS  Article  Google Scholar 

  46. 46

    Van der Meulen, M. F. et al. Polymyositis: an overdiagnosed entity. Neurology 12, 316–321 (2003).

    Article  Google Scholar 

  47. 47

    Brady, S., Squier, W. & Hilton-Jones, D. Clinical assessment determines the diagnosis of inclusion body myositis independently of pathological features. J. Neurol. Neurosurg. Psychiatr. 84, 1240–1246 (2013).

    Article  Google Scholar 

  48. 48

    Rose, M. R. & ENMC IBM Working Group. 188th ENMC International Workshop: Inclusion Body Myositis, 2–4 December 2011, Naarden, The Netherlands. Neuromuscul. Disord. 23, 1044–1055 (2013).

    CAS  Article  Google Scholar 

  49. 49

    Lloyd, T. E. et al. Evaluation and construction of diagnostic criteria for inclusion body myositis. Neurology 29, 426–433 (2014).

    Article  Google Scholar 

  50. 50

    Stenzel, W., Goebel, H. H. & Aronica, E. Review: immunemediated necrotizing myopathies– a heterogeneous group of diseases with specific myopathological features. Appl. Neurobiol. Neuropathol. 38, 632–646 (2012).

    CAS  Article  Google Scholar 

  51. 51

    Allenbach, Y. et al. 224th ENMC International Workshop:: Clinico-sero-pathological classification of immune-mediated necrotizing myopathies Zandvoort, The Netherlands, 14–16 October 2016. Neuromuscul. Disord. 28, 87–99 (2018).

    Article  Google Scholar 

  52. 52

    Van de Vlekkert, J., Hoogendijk, J. E. & de Visser, M. Long-term follow-up of 62 patients with myositis. J. Neurol. 261, 992–998 (2014).

    Article  Google Scholar 

  53. 53

    Pinal-Fernandez, I., Casciola-Rosen, L. A., Christopher-Stine, L., Corse, A. M. & Mammen, A. L. The prevalence of individual histopathologic features varies according to autoantibody status in muscle biopsies from patients with dermatomyositis. J. Rheumatol. 42, 1448–1454 (2015).

    CAS  Article  Google Scholar 

  54. 54

    Allenbach, Y., Benveniste, O., Goebel, H.-H. & Stenzel, W. Integrated classification of inflammatory myopathies. Neuropathol. Appl. Neurobiol. 43, 62–81 (2017).

    CAS  Article  Google Scholar 

  55. 55

    Noguchi, E. et al. Skeletal muscle involvement in antisynthetase syndrome. JAMA Neurol. 74, 992–999 (2017).

    Article  Google Scholar 

  56. 56

    Mozaffar, T. & Pestronk, A. Myopathy with anti-Jo-1 antibodies: Pathology in perimysium and neighbouring muscle fibres. J. Neurol. Neurosurg. Psychiatry, 68, 472–478 (2000).

    CAS  Article  Google Scholar 

  57. 57

    Aouizerate, J. et al. Myofiber HLA-DR espression is a distinctive biomarker for antisynthetase-associated myopathy. Acta Neuropathol. Commun. 23, 154 (2014).

    Article  Google Scholar 

  58. 58

    Mescam-Mancini, L. et al. Anti-Jo-1 antibody-positive patients show a characteristic necrotizing perifascicular myositis. Brain 138, 2485–2492 (2015).

    Article  Google Scholar 

  59. 59

    Stenzel, W. et al. Nuclear actin aggregation is a hallmark of anti-synthetase syndrome–induced dysimmune myopathy. Neurology 84, 1346–1354 (2015).

    CAS  Article  Google Scholar 

  60. 60

    Uruha, A., Suzuki, S., Suzuki, N. & Nishino, I. Perifascicular necrosis in anti-synthetase syndrome beyond anti-Jo-1. Brain 139, e50 (2016).

    Article  Google Scholar 

  61. 61

    Pinal-Fernandez, I. & Mammen, A. L. Spectrum of immune-mediated necrotizing myopathies and their treatments. Curr. Opin. Rheumatol. 28, 619–624 (2016).

    CAS  Article  Google Scholar 

  62. 62

    De Visser, M., Emslie-Smith, A. M. & Engel, A. G. Early ultrastructural alterations in adult dermatomyositis. Capillary abnormalities precede other structural changes in muscle. J. Neurol. Sci. 94, 181–192 (1989).

    CAS  Article  Google Scholar 

  63. 63

    Wedderburn, L. R. et al. International consensus on a proposed score system for muscle biopsy evaluation in patients with juvenile dermatomyositis: a tool for potential use in clinical trials. Arthritis Rheum. 57, 1192–1201 (2007).

    Article  Google Scholar 

  64. 64

    Patel, B. Neelam, K. & Werth, V. P. Applicability of EULAR/ACR classification criteria for dermatomyositis to amyopathic disease. J. Am. Acad. Dermatol. (2017).

  65. 65

    Dalakas, M. C. Polymyositis, dermatomyositis and inclusion-body myositis. N. Engl. J. Med. 325, 1487–1498 (1991).

    CAS  Article  Google Scholar 

  66. 66

    Pestronk, A. Acquired immune and inflammatory myopathies: pathologic classification. Curr. Opin. Rheumatol. 23, 595–604 (2011).

    CAS  Article  Google Scholar 

Download references


The authors thank A. Tjärnlund for being the research coordinator of the International Myositis Classification Criteria Project (IMCCP) and for the critical reading of this manuscript. The authors also thank the IMCCP consortium. The authors thank V. Leclair for her help with Fig. 1. V.P.W. was involved in the development of the Cutaneous Dermatomyositis Disease Area and Severity Index (CDASI); the copyright for this instrument is owned by the University of Pennsylvania. This work was supported by the US NIH (R21 AR066286 and K24-AR 02207) as well as a US Veterans Affairs Merit Review grant (I01BX000706) (V.P.W.). I.E.L. has received grant support from the Swedish Research Council and the Regional Agreement on Medical Training and Clinical Research between the Stockholm County Council and Karolinska Institutet.

Author information




All authors researched the data for the article, provided substantial contributions to discussions of its content, wrote the article and reviewed and/or edited the manuscript before submission.

Corresponding author

Correspondence to Ingrid E. Lundberg.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Related links


Web calculator

PowerPoint slides



A pink, red or purplish colouring around the eyes and eyelids, with or without oedema.

Gottron sign

A symmetrical, occasionally scaly, erythematous eruption over the extensor surfaces of the metacarpophalangeal and interphalangeal joints of the fingers, knees and elbows.

Gottron papules

Red, and often scaly, papules overlying the extensor surfaces of the metacarpophalangeal and interphalangeal joints of the fingers.


Areas of hypopigmentation, hyperpigmentation, telangiectasias and atrophy of the skin.


Dilated capillaries that can be seen in areas of poikiloderma or at the proximal nailfold.

Interface dermatitis

Dermatitis in which the primary pathology involves the dermo-epidermal junction, with basal cell vacuolization, apoptotic keratinocytes and a band-like infiltrate of inflammatory cells at the dermo-epidermal junction; other characteristics in dermatomyositis include lymphocytic perivascular infiltrates and interstitial mucin deposition.

Mechanic's hand

The presence of scaling, fissuring, hyperpigmentation and hyperkeratosis, distributed in a characteristic fashion on the lateral fingers and sometimes the palmar surfaces, fingertips and distal skin, as well on the feet.

Palmar hyperkeratotic papules

Describes scaly verrucous papules on the palm.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Lundberg, I., de Visser, M. & Werth, V. Classification of myositis. Nat Rev Rheumatol 14, 269–278 (2018).

Download citation

Further reading


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing