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Pathogenesis and clinical manifestations of juvenile dermatomyositis and polymyositis

Clare Hutchinson, MDCM, FRCPC
Brian M Feldman, MD, MSc, FRCPC
Section Editors
Thomas JA Lehman, MD
Marc C Patterson, MD, FRACP
Deputy Editor
Elizabeth TePas, MD, MS


Juvenile dermatomyositis (JDM) and juvenile polymyositis (JPM) are rare autoimmune myopathies in childhood. JDM is primarily a capillary vasculopathy, whereas JPM involves direct T cell invasion of muscle fibers similar to that seen in adult polymyositis (PM) [1,2]. (See "Clinical manifestations of dermatomyositis and polymyositis in adults".)

The epidemiology, pathogenesis, and clinical manifestations of JDM and JPM will be reviewed here. Diagnosis and treatment of these disorders are discussed elsewhere. (See "Diagnosis of juvenile dermatomyositis and polymyositis" and "Treatment and prognosis of juvenile dermatomyositis and polymyositis".)


Juvenile dermatomyositis (JDM) is the most common idiopathic inflammatory myopathy of childhood, accounting for approximately 85 percent of cases [3,4]. In population-based studies, JDM has a reported annual incidence that ranges from two to four cases per one million children [5-9]. The peak incidence is from 5 to 10 years of age [8,9]. Girls are affected more often than boys with a two- to fivefold greater rate [7,8,10].

Juvenile polymyositis (JPM) occurs less frequently and accounts for only 3 to 6 percent of childhood idiopathic inflammatory myopathies [3,7].


Although the etiology remains unclear, it has been proposed that juvenile dermatomyositis (JDM) and juvenile polymyositis (JPM) are caused by an autoimmune reaction in genetically susceptible individuals, possibly in response to environmental triggers.


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Literature review current through: Oct 2015. | This topic last updated: Sep 3, 2015.
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  1. Arahata K, Engel AG. Monoclonal antibody analysis of mononuclear cells in myopathies. I: Quantitation of subsets according to diagnosis and sites of accumulation and demonstration and counts of muscle fibers invaded by T cells. Ann Neurol 1984; 16:193.
  2. Banker BQ, Victor M. Dermatomyositis (systemic angiopathy) of childhood. Medicine (Baltimore) 1966; 45:261.
  3. McCann LJ, Juggins AD, Maillard SM, et al. The Juvenile Dermatomyositis National Registry and Repository (UK and Ireland)--clinical characteristics of children recruited within the first 5 yr. Rheumatology (Oxford) 2006; 45:1255.
  4. Ramanan AV, Feldman BM. Clinical features and outcomes of juvenile dermatomyositis and other childhood onset myositis syndromes. Rheum Dis Clin North Am 2002; 28:833.
  5. Oddis CV, Conte CG, Steen VD, Medsger TA Jr. Incidence of polymyositis-dermatomyositis: a 20-year study of hospital diagnosed cases in Allegheny County, PA 1963-1982. J Rheumatol 1990; 17:1329.
  6. Pelkonen PM, Jalanko HJ, Lantto RK, et al. Incidence of systemic connective tissue diseases in children: a nationwide prospective study in Finland. J Rheumatol 1994; 21:2143.
  7. Symmons DP, Sills JA, Davis SM. The incidence of juvenile dermatomyositis: results from a nation-wide study. Br J Rheumatol 1995; 34:732.
  8. Mendez EP, Lipton R, Ramsey-Goldman R, et al. US incidence of juvenile dermatomyositis, 1995-1998: results from the National Institute of Arthritis and Musculoskeletal and Skin Diseases Registry. Arthritis Rheum 2003; 49:300.
  9. Gardner-Medwin JM, Dolezalova P, Cummins C, Southwood TR. Incidence of Henoch-Schönlein purpura, Kawasaki disease, and rare vasculitides in children of different ethnic origins. Lancet 2002; 360:1197.
  10. Pachman LM, Abbott K, Sinacore JM, et al. Duration of illness is an important variable for untreated children with juvenile dermatomyositis. J Pediatr 2006; 148:247.
  11. Harati Y, Niakan E, Bergman EW. Childhood dermatomyositis in monozygotic twins. Neurology 1986; 36:721.
  12. LEONHARDT T. Familial occurrence of collagen diseases. II. Progressive systemic sclerosis and dermatomyositis. Acta Med Scand 1961; 169:735.
  13. Mamyrova G, O'Hanlon TP, Monroe JB, et al. Immunogenetic risk and protective factors for juvenile dermatomyositis in Caucasians. Arthritis Rheum 2006; 54:3979.
  14. Pachman LM, Jonasson O, Cannon RA, Friedman JM. Increased frequency of HLA-B8 in juvenile dermatomyositis. Lancet 1977; 2:1238.
  15. Reed AM, Pachman LM, Hayford J, Ober C. Immunogenetic studies in families of children with juvenile dermatomyositis. J Rheumatol 1998; 25:1000.
  16. Vavrincová P, Havelka S, Cerna M, Stastny P. HLA class II alleles in juvenile dermatomyositis. J Rheumatol Suppl 1993; 37:17.
  17. Pachman LM, Liotta-Davis MR, Hong DK, et al. TNFalpha-308A allele in juvenile dermatomyositis: association with increased production of tumor necrosis factor alpha, disease duration, and pathologic calcifications. Arthritis Rheum 2000; 43:2368.
  18. Rider LG, Artlett CM, Foster CB, et al. Polymorphisms in the IL-1 receptor antagonist gene VNTR are possible risk factors for juvenile idiopathic inflammatory myopathies. Clin Exp Immunol 2000; 121:47.
  19. Mamyrova G, O'Hanlon TP, Sillers L, et al. Cytokine gene polymorphisms as risk and severity factors for juvenile dermatomyositis. Arthritis Rheum 2008; 58:3941.
  20. Niewold TB, Wu SC, Smith M, et al. Familial aggregation of autoimmune disease in juvenile dermatomyositis. Pediatrics 2011; 127:e1239.
  21. Shrestha S, Wershil B, Sarwark JF, et al. Lesional and nonlesional skin from patients with untreated juvenile dermatomyositis displays increased numbers of mast cells and mature plasmacytoid dendritic cells. Arthritis Rheum 2010; 62:2813.
  22. Pachman LM. Inflammatory myopathy in children. Rheum Dis Clin North Am 1994; 20:919.
  23. Rider LG, Miller FW, Targoff IN, et al. A broadened spectrum of juvenile myositis. Myositis-specific autoantibodies in children. Arthritis Rheum 1994; 37:1534.
  24. Feldman BM, Reichlin M, Laxer RM, et al. Clinical significance of specific autoantibodies in juvenile dermatomyositis. J Rheumatol 1996; 23:1794.
  25. Gunawardena H, Wedderburn LR, North J, et al. Clinical associations of autoantibodies to a p155/140 kDa doublet protein in juvenile dermatomyositis. Rheumatology (Oxford) 2008; 47:324.
  26. Kobayashi I, Okura Y, Yamada M, et al. Anti-melanoma differentiation-associated gene 5 antibody is a diagnostic and predictive marker for interstitial lung diseases associated with juvenile dermatomyositis. J Pediatr 2011; 158:675.
  27. Artlett CM, Ramos R, Jiminez SA, et al. Chimeric cells of maternal origin in juvenile idiopathic inflammatory myopathies. Childhood Myositis Heterogeneity Collaborative Group. Lancet 2000; 356:2155.
  28. Reed AM, Picornell YJ, Harwood A, Kredich DW. Chimerism in children with juvenile dermatomyositis. Lancet 2000; 356:2156.
  29. Elst EF, Klein M, de Jager W, et al. Hsp60 in inflamed muscle tissue is the target of regulatory autoreactive T cells in patients with juvenile dermatomyositis. Arthritis Rheum 2008; 58:547.
  30. Christensen ML, Pachman LM, Schneiderman R, et al. Prevalence of Coxsackie B virus antibodies in patients with juvenile dermatomyositis. Arthritis Rheum 1986; 29:1365.
  31. Tang TT, Sedmak GV, Siegesmund KA, McCreadie SR. Chronic myopathy associated with coxsackievirus type A9. A combined electron microscopical and viral isolation study. N Engl J Med 1975; 292:608.
  32. Webster AD, Tripp JH, Hayward AR, et al. Echovirus encephalitis and myositis in primary immunoglobulin deficiency. Arch Dis Child 1978; 53:33.
  33. Pachman LM, Hayford JR, Hochberg MC. Seasonal onset in juvenile dermatomyositis (JDMS): an epidemiological study. Arthritis Rheum 1992; 35:S88.
  34. Massa M, Costouros N, Mazzoli F, et al. Self epitopes shared between human skeletal myosin and Streptococcus pyogenes M5 protein are targets of immune responses in active juvenile dermatomyositis. Arthritis Rheum 2002; 46:3015.
  35. Pachman LM, Lipton R, Ramsey-Goldman R, et al. History of infection before the onset of juvenile dermatomyositis: results from the National Institute of Arthritis and Musculoskeletal and Skin Diseases Research Registry. Arthritis Rheum 2005; 53:166.
  36. Manlhiot C, Liang L, Tran D, et al. Assessment of an infectious disease history preceding juvenile dermatomyositis symptom onset. Rheumatology (Oxford) 2008; 47:526.
  37. Pachman LM, Hayford JR, Hochberg MC, et al. New-onset juvenile dermatomyositis: comparisons with a healthy cohort and children with juvenile rheumatoid arthritis. Arthritis Rheum 1997; 40:1526.
  38. Pachman LM, Litt DL, Rowley AH, et al. Lack of detection of enteroviral RNA or bacterial DNA in magnetic resonance imaging-directed muscle biopsies from twenty children with active untreated juvenile dermatomyositis. Arthritis Rheum 1995; 38:1513.
  39. Stockton D, Doherty VR, Brewster DH. Risk of cancer in patients with dermatomyositis or polymyositis, and follow-up implications: a Scottish population-based cohort study. Br J Cancer 2001; 85:41.
  40. Dugan EM, Huber AM, Miller FW, et al. Photoessay of the cutaneous manifestations of the idiopathic inflammatory myopathies. Dermatol Online J 2009; 15:1.
  41. Constantin T, Ponyi A, Orbán I, et al. National registry of patients with juvenile idiopathic inflammatory myopathies in Hungary--clinical characteristics and disease course of 44 patients with juvenile dermatomyositis. Autoimmunity 2006; 39:223.
  42. Akikusa JD, Tennankore DK, Levin AV, Feldman BM. Eye findings in patients with juvenile dermatomyositis. J Rheumatol 2005; 32:1986.
  44. Schmeling H, Stephens S, Goia C, et al. Nailfold capillary density is importantly associated over time with muscle and skin disease activity in juvenile dermatomyositis. Rheumatology (Oxford) 2011; 50:885.
  45. Smith RL, Sundberg J, Shamiyah E, et al. Skin involvement in juvenile dermatomyositis is associated with loss of end row nailfold capillary loops. J Rheumatol 2004; 31:1644.
  46. Bowyer SL, Blane CE, Sullivan DB, Cassidy JT. Childhood dermatomyositis: factors predicting functional outcome and development of dystrophic calcification. J Pediatr 1983; 103:882.
  47. Crowe WE, Bove KE, Levinson JE, Hilton PK. Clinical and pathogenetic implications of histopathology in childhood polydermatomyositis. Arthritis Rheum 1982; 25:126.
  48. Huber AM, Lang B, LeBlanc CM, et al. Medium- and long-term functional outcomes in a multicenter cohort of children with juvenile dermatomyositis. Arthritis Rheum 2000; 43:541.
  49. Sallum AM, Pivato FC, Doria-Filho U, et al. Risk factors associated with calcinosis of juvenile dermatomyositis. J Pediatr (Rio J) 2008; 84:68.
  50. Blane CE, White SJ, Braunstein EM, et al. Patterns of calcification in childhood dermatomyositis. AJR Am J Roentgenol 1984; 142:397.
  51. Pachman LM, Hayford JR, Chung A, et al. Juvenile dermatomyositis at diagnosis: clinical characteristics of 79 children. J Rheumatol 1998; 25:1198.
  52. Tansley SL, Betteridge ZE, Shaddick G, et al. Calcinosis in juvenile dermatomyositis is influenced by both anti-NXP2 autoantibody status and age at disease onset. Rheumatology (Oxford) 2014; 53:2204.
  53. Marhaug G, Shah V, Shroff R, et al. Age-dependent inhibition of ectopic calcification: a possible role for fetuin-A and osteopontin in patients with juvenile dermatomyositis with calcinosis. Rheumatology (Oxford) 2008; 47:1031.
  54. Euwer RL, Sontheimer RD. Amyopathic dermatomyositis: a review. J Invest Dermatol 1993; 100:124S.
  55. Plamondon S, Dent PB. Juvenile amyopathic dermatomyositis: results of a case finding descriptive survey. J Rheumatol 2000; 27:2031.
  56. Stonecipher MR, Jorizzo JL, White WL, et al. Cutaneous changes of dermatomyositis in patients with normal muscle enzymes: dermatomyositis sine myositis? J Am Acad Dermatol 1993; 28:951.
  57. Tse S, Lubelsky S, Gordon M, et al. The arthritis of inflammatory childhood myositis syndromes. J Rheumatol 2001; 28:192.
  58. Bingham A, Mamyrova G, Rother KI, et al. Predictors of acquired lipodystrophy in juvenile-onset dermatomyositis and a gradient of severity. Medicine (Baltimore) 2008; 87:70.
  59. Huemer C, Kitson H, Malleson PN, et al. Lipodystrophy in patients with juvenile dermatomyositis--evaluation of clinical and metabolic abnormalities. J Rheumatol 2001; 28:610.
  60. Verma S, Singh S, Bhalla AK, Khullar M. Study of subcutaneous fat in children with juvenile dermatomyositis. Arthritis Rheum 2006; 55:564.
  61. Pope E, Janson A, Khambalia A, Feldman B. Childhood acquired lipodystrophy: a retrospective study. J Am Acad Dermatol 2006; 55:947.
  62. Kobayashi I, Yamada M, Takahashi Y, et al. Interstitial lung disease associated with juvenile dermatomyositis: clinical features and efficacy of cyclosporin A. Rheumatology (Oxford) 2003; 42:371.
  63. Kobayashi N, Takezaki S, Kobayashi I, et al. Clinical and laboratory features of fatal rapidly progressive interstitial lung disease associated with juvenile dermatomyositis. Rheumatology (Oxford) 2015; 54:784.
  64. Downey EC Jr, Woolley MM, Hanson V. Required surgical therapy in the pediatric patient with dermatomyositis. Arch Surg 1988; 123:1117.
  65. Mamyrova G, Kleiner DE, James-Newton L, et al. Late-onset gastrointestinal pain in juvenile dermatomyositis as a manifestation of ischemic ulceration from chronic endarteropathy. Arthritis Rheum 2007; 57:881.
  66. Mitchell JP, Dennis GJ, Rider LG. Juvenile dermatomyositis presenting with anasarca: A possible indicator of severe disease activity. J Pediatr 2001; 138:942.