Diagnosis of juvenile dermatomyositis and polymyositis
- Clare Hutchinson, MDCM, FRCPC
Clare Hutchinson, MDCM, FRCPC
- Pediatric Rheumatologist
- University of Toronto
- Brian M Feldman, MD, MSc, FRCPC
Brian M Feldman, MD, MSc, FRCPC
- Professor of Pediatrics
- University of Toronto
- Section Editors
- Thomas JA Lehman, MD
Thomas JA Lehman, MD
- Section Editor — Pediatric Rheumatology
- Professor of Clinical Pediatrics
- Cornell University Medical College
- Marc C Patterson, MD, FRACP
Marc C Patterson, MD, FRACP
- Section Editor — Pediatric Neurology
- Professor of Neurology, Pediatrics, and Medical Genetics
- Chair, Division of Child and Adolescent Neurology
- Mayo Clinic College of Medicine
Juvenile dermatomyositis (JDM) and juvenile polymyositis (JPM) are rare autoimmune myopathies affecting children. JDM is characterized primarily as a capillary vasculopathy, whereas JPM involves direct T cell invasion of muscle fibers similar to that seen in adult polymyositis [1,2]. (See "Clinical manifestations of dermatomyositis and polymyositis in adults".)
JDM is the more common of the two disorders accounting for approximately 85 percent of idiopathic inflammatory myopathies of childhood. JPM accounts for only 3 to 6 percent of cases.
The diagnosis of JDM and JPM will be reviewed here. The pathogenesis, clinical manifestations, and treatment of these disorders are discussed elsewhere. (See "Pathogenesis and clinical manifestations of juvenile dermatomyositis and polymyositis" and "Treatment and prognosis of juvenile dermatomyositis and polymyositis".)
CLASSIFICATION AND DIAGNOSTIC CRITERIA
In 1975, Bohan and Peter proposed a classification schema and diagnostic criteria for the various forms of myositis including juvenile dermatomyositis (JDM) . Their diagnostic criteria for JDM included all of the following findings :
●Symmetrical weakness of the proximal muscles.
- 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.
- Banker BQ, Victor M. Dermatomyositis (systemic angiopathy) of childhood. Medicine (Baltimore) 1966; 45:261.
- Bohan A, Peter JB. Polymyositis and dermatomyositis (first of two parts). N Engl J Med 1975; 292:344.
- Brown VE, Pilkington CA, Feldman BM, et al. An international consensus survey of the diagnostic criteria for juvenile dermatomyositis (JDM). Rheumatology (Oxford) 2006; 45:990.
- 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.
- Rider LG, Koziol D, Giannini EH, et al. Validation of manual muscle testing and a subset of eight muscles for adult and juvenile idiopathic inflammatory myopathies. Arthritis Care Res (Hoboken) 2010; 62:465.
- Manual Muscle Testing Procedures for MMT8 Testing. http://www.niehs.nih.gov/research/resources/assets/docs/mmt8_grading_and_testing_procedures_for_the_abbreviated_8_muscle_groups.pdf (Accessed on July 22, 2013).
- Harris-Love MO, Shrader JA, Koziol D, et al. Distribution and severity of weakness among patients with polymyositis, dermatomyositis and juvenile dermatomyositis. Rheumatology (Oxford) 2009; 48:134.
- Rider LG, Giannini EH, Harris-Love M, et al. Defining Clinical Improvement in Adult and Juvenile Myositis. J Rheumatol 2003; 30:603.
- Lovell DJ, Lindsley CB, Rennebohm RM, et al. Development of validated disease activity and damage indices for the juvenile idiopathic inflammatory myopathies. II. The Childhood Myositis Assessment Scale (CMAS): a quantitative tool for the evaluation of muscle function. The Juvenile Dermatomyositis Disease Activity Collaborative Study Group. Arthritis Rheum 1999; 42:2213.
- 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.
- Dolezalova P, Young SP, Bacon PA, Southwood TR. Nailfold capillary microscopy in healthy children and in childhood rheumatic diseases: a prospective single blind observational study. Ann Rheum Dis 2003; 62:444.
- Spencer-Green G, Schlesinger M, Bove KE, et al. Nailfold capillary abnormalities in childhood rheumatic diseases. J Pediatr 1983; 102:341.
- Christen-Zaech S, Seshadri R, Sundberg J, et al. Persistent association of nailfold capillaroscopy changes and skin involvement over thirty-six months with duration of untreated disease in patients with juvenile dermatomyositis. Arthritis Rheum 2008; 58:571.
- 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.
- Guzmán J, Petty RE, Malleson PN. Monitoring disease activity in juvenile dermatomyositis: the role of von Willebrand factor and muscle enzymes. J Rheumatol 1994; 21:739.
- Bohan A, Peter JB. Polymyositis and dermatomyositis (second of two parts). N Engl J Med 1975; 292:403.
- 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.
- Hernandez RJ, Sullivan DB, Chenevert TL, Keim DR. MR imaging in children with dermatomyositis: musculoskeletal findings and correlation with clinical and laboratory findings. AJR Am J Roentgenol 1993; 161:359.
- Park JH, Niermann KJ, Ryder NM, et al. Muscle abnormalities in juvenile dermatomyositis patients: P-31 magnetic resonance spectroscopy studies. Arthritis Rheum 2000; 43:2359.
- Tzaribachev N, Well C, Schedel J, Horger M. Whole-body MRI: a helpful diagnostic tool for juvenile dermatomyositis case report and review of the literature. Rheumatol Int 2009; 29:1511.
- Crowe WE, Bove KE, Levinson JE, Hilton PK. Clinical and pathogenetic implications of histopathology in childhood polydermatomyositis. Arthritis Rheum 1982; 25:126.
- Miles L, Bove KE, Lovell D, et al. Predictability of the clinical course of juvenile dermatomyositis based on initial muscle biopsy: a retrospective study of 72 patients. Arthritis Rheum 2007; 57:1183.
- Wedderburn LR, Varsani H, Li CK, 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 2007; 57:1192.
- Haas RH, Dyck RF, Dubowitz V, Pepys MB. C-reactive protein in childhood dermatomyositis. Ann Rheum Dis 1982; 41:483.
- Bloom BJ, Tucker LB, Miller LC, Schaller JG. von Willebrand factor in juvenile dermatomyositis. J Rheumatol 1995; 22:320.
- Rider LG, Miller FW, Targoff IN, et al. A broadened spectrum of juvenile myositis. Myositis-specific autoantibodies in children. Arthritis Rheum 1994; 37:1534.
- Rider LG, Shah M, Mamyrova G, et al. The myositis autoantibody phenotypes of the juvenile idiopathic inflammatory myopathies. Medicine (Baltimore) 2013; 92:223.
- Compeyrot-Lacassagne S, Feldman BM. Inflammatory myopathies in children. Rheum Dis Clin North Am 2007; 33:525.
- CLASSIFICATION AND DIAGNOSTIC CRITERIA
- Physical examination
- - Rash
- - Muscle strength
- - Nailfold capillaroscopy
- Muscle enzymes
- Magnetic resonance imaging
- Muscle biopsy
- Other tests
- Our approach
- DIFFERENTIAL DIAGNOSIS
- Noninflammatory myopathy
- Other forms of myositis
- Disorders of denervation or neuropathy
- SUMMARY AND RECOMMENDATIONS