We searched five databases: Medline (1950 to April week 4, 2007); Embase (1980 to week 18, 2007); Cinahl (1982 to May week 1, 2007); Evidence-Based Medicine Reviews (including the Cochrane Library); and Allied and Complementary Medicine (1985 to April, 2007). Any article on myositis in children was eligible for inclusion, with no restrictions on language or year of publication. The main search terms were “dermatomyositis”, “myositis”, “polymyositis”, “orbital myositis”, “overlap
SeminarJuvenile dermatomyositis and other idiopathic inflammatory myopathies of childhood
Introduction
Juvenile dermatomyositis is a rare, often chronic, autoimmune disease with onset during childhood. It is a systemic vasculopathy characterised by symmetrical proximal muscle weakness, raised serum concentrations of muscle enzymes, and pathognomonic skin rashes that include the heliotrope rash over the eyelids and Gottron's papules over the extensor joint surfaces (figure 1). This disease is classified as one of the idiopathic inflammatory myopathies (table 1); the adult forms are more common.1, 2, 3, 4 In this Seminar, we will focus on juvenile dermatomyositis, but refer to other idiopathic inflammatory myopathies with juvenile onset where relevant. We review some important advances in the understanding of the causes, epidemiology, pathophysiology, clinical features, and treatment of idiopathic inflammatory myopathies in childhood.
Section snippets
Causes and epidemiology
The incidence of juvenile dermatomyositis in the USA is 3·2 per million children per year,5 which is similar to that in the UK.6 The average age at onset is 7 years, but 25% of patients are younger than 4 years at onset.7 In the USA, the ratio of girls to boys is 2·3 to 1,7 compared with 5 to 1 in the UK.6 Rash is the first symptom to be recognised in half the children and weakness is the first symptom in a quarter.8
Childhood idiopathic inflammatory myopathies, like other autoimmune diseases,
Pathological changes and pathophysiology
We have focused on new ideas about disease pathogenesis (figure 2) in juvenile dermatomyositis, and idiopathic inflammatory myopathies in general, rather than provide a complete review. Juvenile dermatomyositis is a vasculopathic condition.25 Typical histological changes in the muscle include swelling of the capillary endothelium with obliteration of the lumen, perifascicular atrophy, perivascular inflammation, muscle degeneration and regeneration, and the presence of tubuloreticular inclusions
Diagnostic criteria
Juvenile dermatomyositis is usually considered in the differential diagnosis either when erythematous rashes arise on the face or extremities or when acquired symmetrical muscle weakness is present. Many conditions might present similarly and should be considered in the differential diagnosis (table 2).43, 44 The diagnosis of juvenile dermatomyositis is mainly made through a constellation of clinical and laboratory tests, as applied in the 1975 criteria by Bohan and Peter.45, 46 Only two-thirds
Clinical features
In addition to proximal, usually progressive, muscle weakness and characteristic skin rashes (Gottron's papules or the heliotrope eyelid rash), the presenting features of juvenile dermatomyositis are protean (Figure 3, Figure 4,53, 54, 55, 56 panel). Nonetheless, some characteristic features deserve further discussion. Dystrophic calcification (figure 3D) occurs in up to 30% of patients.56, 57 The sites most frequently affected are pressure points: elbows, knees, digits, and buttocks.
Heterogeneity of childhood idiopathic inflammatory myopathies
Childhood idiopathic inflammatory myopathies can be divided into more homogeneous clinicopathological or serological subsets with distinctive epidemiology, and clinical, pathological, or prognostic features (Table 1, Table 3).1 Juvenile dermatomyositis is the most common subset, representing up to 85% of childhood idiopathic inflammatory myopathies.48, 53 The two other major subsets of idiopathic inflammatory myopathies are juvenile polymyositis, in which the characteristic rashes are absent,
Clinical course
Typically, children with myositis are followed up by serial examination of muscle strength, function, rash, other organs, and serum concentrations of muscle enzymes. However, tests for muscle enzymes are not very sensitive (more than 20% of patients have a normal creatine kinase concentration at diagnosis8) and frequently become normal with corticosteroid treatment even in active disease. Two international collaborative study groups have standardised and validated measures of disease activity
Treatment
Treatment for childhood idiopathic inflammatory myopathies have not been assessed in randomised controlled trials. Our best understanding of treatment comes from observational studies and clinical experience. Since the 1970s, standard treatment for juvenile dermatomyositis has been high-dose daily oral corticosteroids (eg, up to 2 mg/kg per day of prednisone, often in divided doses), which is continued until clinical and laboratory improvement are evident and then slowly reduced over at least a
Search strategy and selection criteria
References (138)
- et al.
Classification and treatment of the juvenile idiopathic inflammatory myopathies
Rheum Dis Clin North Am
(1997) The heterogeneity of juvenile myositis
Autoimmun Rev
(2007)- et al.
Polymyositis and dermatomyositis
Lancet
(2003) - et al.
Increased frequency of HLA-B8 in juvenile dermatomyositis
Lancet
(1977) - et al.
Molecular genetic studies of major histocompatibility complex genes in children with juvenile dermatomyositis: increased risk associated with HLA-DQA1 *0501
Human Immunol
(1991) - et al.
Dermatomyositis, polymyositis, and Coxsackie-B-virus infection
Lancet
(1987) - et al.
Genetic and environmental risk factors for idiopathic inflammatory myopathies
Rheum Dis Clin North Am
(2002) - et al.
MxA gene expression in juvenile dermatomyositis peripheral blood mononuclear cells: association with muscle involvement
Clin Immunol
(2006) - et al.
Apoptosis in the skeletal muscle of untreated children with juvenile dermatomyositis: impact of duration of untreated disease
Clin Immunol
(2007) - et al.
Difference in adhesion molecule expression (ICAM-1 and VCAM-1) in juvenile and adult dermatomyositis, polymyositis and inclusion body myositis
Autoimmun Rev
(2006)
Chimeric cells of maternal origin in juvenile idiopathic inflammatory myopathies. Childhood Myositis Heterogeneity Collaborative Group
Lancet
Chimerism in children with juvenile dermatomyositis
Lancet
Inflammatory myopathies in children
Pediatr Clin North Am
Clinical features and outcomes of juvenile dermatomyositis and other childhood onset myositis syndromes
Rheum Dis Clin North Am
Juvenile dermatomyositis. Pathophysiology and disease expression
Pediatr Clin North Am
Childhood dermatomyositis: factors predicting functional outcome and development of dystrophic calcification
J Pediatr
Course of treated juvenile dermatomyositis
J Pediatr
Outcome assessment in the adult and juvenile idiopathic inflammatory myopathies
Rheum Dis Clin North Am
Juvenile dermatomyositis presenting with anasarca: a possible indicator of severe disease activity
J Pediatr
Childhood acquired lipodystrophy: a retrospective study
J Am Acad Dermatol
Amyopathic dermatomyositis: retrospective review of 37 cases
J Am Acad Dermatol
Macrophagic myofasciitis in childhood: a controversial entity
Pediatr Neurol
Contribution of autoantibodies to the diagnosis and nosology of inflammatory muscle disease
Joint Bone Spine
A new approach to the classification of idiopathic inflammatory myopathy: myositis-specific autoantibodies define useful homogeneous patient groups
Medicine
US incidence of juvenile dermatomyositis, 1995–1998: results from the National Institute of Arthritis and Musculoskeletal and Skin Diseases Registry
Arthritis Rheum
The incidence of juvenile dermatomyositis: results from a nation-wide study
Br J Rheumatol
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
Juvenile dermatomyositis at diagnosis: clinical characteristics of 79 children
J Rheumatol
The role of genetic factors in autoimmune disease: implications for environmental research
Environ Health Perspect
Immunogenetic risk and protective factors for juvenile dermatomyositis in Caucasians
Arthritis Rheum
TNFalpha-308A allele in juvenile dermatomyositis: association with increased production of tumor necrosis factor alpha, disease duration, and pathologic calcifications
Arthritis Rheum
Polymorphisms in the IL-1 receptor antagonist gene VNTR are possible risk factors for juvenile idiopathic inflammatory myopathies
Clin Exp Immunol
Prevalence of Coxsackie B virus antibodies in patients with juvenile dermatomyositis
Arthritis Rheum
Seasonal birth patterns in myositis subgroups suggest an etiologic role of early environmental exposures
Arthritis Rheum
New-onset juvenile dermatomyositis: comparisons with a healthy cohort and children with juvenile rheumatoid arthritis
Arthritis Rheum
Childhood polymyositis: a case-control study
Am J Epidemiol
Self epitopes shared between human skeletal myosin and Streptococcus pyogenes M5 protein are targets of immune responses in active juvenile dermatomyositis
Arthritis Rheum
Dermatomyositis-like syndrome due to toxoplasma
Br J Dermatol
Parvovirus B19 and onset of juvenile dermatomyositis
JAMA
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
Dermatomyositis (systemic angiopathy) of childhood
Medicine
International consensus on a proposed score system for muscle biopsy evaluation in patients with JDM, for potential use in clinical trials
Arthritis Rheum
Predictability of the clinical course of juvenile dermatomyositis based on initial muscle biopsy: a retrospective study of 72 patients
Arthritis Rheum
Gene expression profiling in DQA1*0501 children with untreated dermatomyositis: a novel model of pathogenesis
J Immunol
An interferon signature in the peripheral blood of dermatomyositis patients is associated with disease activity
Mol Med
MHC class I overexpression on muscles in early juvenile dermatomyositis
J Rheum
Interleukin-1alpha expression in capillaries and major histocompatibility complex class I expression in type II muscle fibers from polymyositis and dermatomyositis patients: important pathogenic features independent of inflammatory cell clusters in muscle tissue
Arthritis Rheum
Signs of inflammation in both symptomatic and asymptomatic muscles from patients with polymyositis and dermatomyositis
Ann Rheum Dis
Activation of the endoplasmic reticulum stress response in autoimmune myositis: potential role in muscle fiber damage and dysfunction
Arthritis Rheum
Increased CD40 expression on muscle cells of polymyositis and dermatomyositis: role of CD40-CD40 ligand interaction in IL-6, IL-8, IL-15, and monocyte chemoattractant protein-1 production
J Immunol
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2022, Seminars in Arthritis and RheumatismCitation Excerpt :The course of the disease in our patients is quite similar to our previous reports [2,24], and similar to that reported by other centers [4]. However, in one study done in Melbourne, the number of patients with polycyclic disease was considerably higher at 17.7% [8,19]. This likely reflects a difference in the way the term has been defined; for our definition we require a period of greater than 12 weeks in clinical and laboratory remission while off all medications before relapse.