Juvenile Idiopathic Inflammatory Myopathies Research Articles

Inclusion Body Myositis in Children: Does it Exist?

Context: Sporadic inclusion body myositis (sIBM) is a rare type of juvenile idiopathic inflammatory myopathies (JIIMs). It mainly affects skeletal muscles but can also affect the skin and other organs in the body. Sporadic inclusion body myositis prevalence in children under 18 years old is very rare. Objectives: This review provides an overview of the evidence of sIBM in children, discusses the possible clinical and pathological features, and explores the proposed pathogenesis. Methods: A literature review of over 44 articles in PubMed and other medical libraries, such as Google Scholar and Web of Science, was carried out using terms such as JIIM, IBM, Inflammatory Myopathies in Children, and Inherited IBM. Two documented reports for sIBM were found, and the rest included the disease pathogenesis, prevalence of inherited IBM, and other myopathies in children. Results: This review discussed the prevalence and incidence of JIIM, in particular sIBM in children. While IBM is typically sporadic, there have been rare cases where it is familial and inherited. Genetic susceptibility factors are believed to play a role in sIBM. Most patients with sIBM are over 50 years old and experience significant weakness in the quadriceps; however, patients with inherited IBM (h-IBM) typically present earlier in adulthood with a distinct pattern of weakness. Sporadic inclusion body myositis can be misdiagnosed as other forms of myopathies, such as juvenile dermatomyositis (JDM) or limb-girdle muscular dystrophy (LGMD), during the early stages of the disease. The exact causes of sIBM are still unknown; however, environmental factors, genetic predispositions, and immune dysregulation might contribute to the pathogenesis of the disease. Conclusions: Sporadic inclusion body myositis is a rare form of JIIMs. Its early diagnosis in children can be challenging due to the presence of other coexisting diseases. Discussions have revolved around potential environmental factors, such as viral infections, specific myositis-specific antibodies (MSAs), such as anti-Ro52, and possibly certain human leukocyte antigen (HLA) haplotypes. Given the rarity of reported cases of sIBM in children, it is important to encourage further studies to better understand the underdiagnosed instances of this condition.

Performance of the 2017 EULAR/ACR Classification Criteria for adult and juvenile idiopathic inflammatory myopathies and their major subgroups: a scoping review.

The 2017 EULAR/ACR classification criteria for adult/juvenile idiopathic inflammatory myopathies (IIM) were established using a data-driven approach by an international group of myositis experts to allow classification of IIM and its major subtypes. Since their publication, the performance of the criteria has been tested in multiple cohorts worldwide and significant limitations have been identified. Moreover, the understanding and classification of IIM have evolved since 2017. This scoping review was undertaken as part of a large international project to revise the EULAR/ACR criteria and aims to i) summarise the evidence from the current literature on the performance characteristics of the 2017 EULAR/ACR classification criteria in various cohorts and IIM subtypes, and ii) delineate the factors that need to be considered in the revision of the classification criteria. A systematic search of Medline (via PubMed), Cumulative Index to Nursing and Allied Health Literature, and conference abstract archives was conducted independently by three investigators for studies on the EULAR/ACR criteria published between October 2017 and January 2023. This scoping review of 19 articles and 13 abstracts revealed overall good performance characteristics of the EULAR/ACR criteria for IIM, yet deficiencies in lack of inclusion of certain IIM subtypes, such as immune mediated necrotising myopathy, amyopathic dermatomyositis, antisynthetase syndrome and overlap myositis. Published modifications that may improve the performance characteristics of the criteria for classification of IIM subtypes were also summarised. The results of this review suggest that a revision of the EULAR/ACR criteria is warranted.

The impact of the COVID-19 pandemic on patients with juvenile idiopathic inflammatory myopathies

BackgroundThroughout the COVID-19 pandemic, there have been concerns regarding the risks of infection in patients with autoimmune disease. In this study, we investigated the impact of the pandemic on patients with juvenile idiopathic inflammatory myopathies (JIIM).MethodsData were collected using a patient/caregiver survey via Research Electronic Data Capture (REDCap) database. Eligibility included JIIM diagnosis and current age less than 21 years old. Surveys were distributed via the CureJM organization, social media, Childhood Arthritis and Rheumatology Research Alliance (CARRA) network and Dr. Peter Dent Pediatric Rheumatology Bulletin Board.ResultsEighty-four respondents accessed the survey, 70 (83%) consented to participate, and 54 out of 70 completed the full survey (77%). Twenty-seven out of 57 patients (47%) tested positive for COVID-19, with 7 (12%) testing positive more than once. Despite broad usage of immunosuppressive medications, 24 out of 27 (89%) reported mild symptoms with none requiring hospitalization. Four patients reported a flare of JIIM symptoms after COVID-19; three of whom held immunomodulatory medications during their infection. Thirty-seven out of 54 respondents (69%) reported vaccination against COVID-19, with 9 out of 37 (24%) reporting minor vaccine side effects and one reporting JIIM flare post vaccination. Twenty-one out of 54 (39%) respondents reported psychosocial concerns related to the COVID-19 pandemic.ConclusionsPatients with JIIM, including those on multiple immunosuppressive medications, had mild symptoms related to COVID-19. Most patients tolerated COVID-19 vaccination well. Few patients had disease flare post-COVID-19 or vaccination. Mental health concerns were demonstrated in JIIM patients during the COVID-19 pandemic.

Clinical features and outcomes of children’s interstitial lung disease accompanied with connective tissue disease: A prospective cohort study

BackgroundMedical complexity of childhood interstitial lung disease (chILD) with connective tissue disease (CTD) poses a considerable challenge to pediatricians. MethodsClinical characteristics, laboratory findings, pulmonary function tests (PFTs), treatments and outcomes obtained for patients with CTD-chILD were analyzed in a prospective study. ResultsPatients’ median age at diagnosis was 7 years old. About 29.4% (15/51) suffered rapidly progressive childhood ILD (RP-chILD) with a high mortality rate (33.3%, 5/15), and the incidence of RP-chILD in juvenile idiopathic inflammatory myopathies was as high as 41.6% and the mortality rate was 30% (3/10). More than 70% patients had decreased diffusion capacity. The mean interval from symptoms-onset to diagnosis was 11.3 months. Compared to chILD with known CTD, the chILD proceeded CTD had a longer diagnosis interval, higher mortality, hospital stays and costs (P < 0.05). Lung imaging (33.3%) and lung function (72.7%) were partially reversible. The average survival time was 68.6 months. Cox univariate analysis showed that HRCT score ≥3, experiencing RP-chILD, cyanosis, acute respiratory distress syndrome (ARDS) and CD4 T cell <200 were significant predictors of death for chILD, whereas Cox multivariate analysis showed that ARDS was significant predictor of death for CTD-chILD, while IVIG support combined with corticosteroids and immunosuppressants was a protective factor. ConclusionsCare providers should conduct an assessment for CTD in chILD as a longer interval between the diagnosis of chILD and the CTD is associated with increased mortality. Complications as ARDS predict poor outcome in CTD-chILD, while IVIG support combined with corticosteroids and immunosuppressants is a protective factor.

Impact of SARS-CoV-2 on the clinical presentation of juvenile idiopathic inflammatory myopathies

BackgroundGrowing evidence suggests that infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may trigger idiopathic inflammatory myopathies (IIM). Few studies have described individual juvenile IIM (JIIM) cases following SARS-CoV-2 infection, and none explored its potential effects on JIIM clinical presentation. We aim to investigate the impact of SARS-CoV-2 on JIIM in patients diagnosed before and after the onset of the Coronavirus Disease 2019 (COVID-19) pandemic.MethodsPatients diagnosed with JIIM before age 19 at The Children’s Hospital at Montefiore were included. Demographics, clinical and laboratory data, and evidence of SARS-CoV-2 exposure were collected retrospectively. Patients were grouped by pre-COVID-19 (before January 1, 2020) and post-COVID-19 (January 1, 2020, or later). Descriptive statistics were used to summarize each variable. Non-parametric testing was performed using Fischer’s exact test and Mann-Whitney U test.ResultsFifty-one patients were included, 13 (25%) diagnosed in the post-COVID-19 era. Of these, 10 (77%) had onset of JIIM symptoms after January 1, 2020; 6 (60%) with known or suspected SARS-CoV-2 exposure. Though not statistically significant, post-pandemic patients tended to be older, female, and have non-specific cutaneous manifestations. Despite reported delays in care for other pediatric diagnoses during the pandemic, fewer post-pandemic patients had delays in JIIM diagnosis.ConclusionsThis is the first study to explore the effects of SARS-CoV-2 on JIIM clinical presentation. While our exploratory single-center study did not find significant differences in JIIM diagnosed pre- and post-pandemic, larger prospective multicenter studies are warranted to evaluate this association and to explore clinical variances over time.

Alternative Therapies to Immunoglobulin for Idiopathic Inflammatory Myopathies

&#x0D; We did not find any evidence regarding the clinical effectiveness and safety of alternative treatments to IV Immunoglobulin (IVIG) compared to IVIG or placebo for idiopathic inflammatory myopathies (IIM) that met our inclusion criteria for this review.&#x0D; Three evidence-based guidelines provide recommendations regarding IVIG and other drugs to manage IIM. However, we did not find any recommendations regarding alternative treatments to IVIG specifically.&#x0D; Rituximab may be considered as another option to IVIG to treat IIM-related skeletal muscle inflammation (1 guideline) or skin manifestations (1 guideline) resistant to treatment with steroids.&#x0D; In juvenile IIM, rituximab or IVIG can be used as adjunct care in case of treatment failure.&#x0D;

Juvenile idiopathic inflammatory myositis: an update on pathophysiology and clinical care.

The childhood-onset or juvenile idiopathic inflammatory myopathies (JIIMs) are a heterogenous group of rare and serious autoimmune diseases of children and young people that predominantly affect the muscles and skin but can also involve other organs, including the lungs, gut, joints, heart and central nervous system. Different myositis-specific autoantibodies have been identified that are associated with different muscle biopsy features, as well as with different clinical characteristics, prognoses and treatment responses. Thus, myositis-specific autoantibodies can be used to subset JIIMs into sub-phenotypes; some of these sub-phenotypes parallel disease seen in adults, whereas others are distinct from adult-onset idiopathic inflammatory myopathies. Although treatments and management have much improved over the past decade, evidence is still lacking for many of the current treatments and few validated prognostic biomarkers are available with which to predict response to treatment, comorbidities (such as calcinosis) or outcome. Emerging data on the pathogenesis of the JIIMs are leading to proposals for new trials and tools for monitoring disease.

Retinal changes in patients with idiopathic inflammatory myopathies: A case-control study in the MyoCite cohort.

Retinal changes are the window to systemic vasculature. Therefore, we explored retinal changes in patients with Idiopathic inflammatory myopathies (IIM) as a surrogate for vascular health. Adult and Juvenile IIM patients (2017 ACR/EULAR criteria), visiting a tertiary care center in 2021 were enrolled for detailed ophthalmic examination in comparison with healthy controls (HC). Patients with conditions that precluded thorough posterior chamber examination were excluded. Scale variables are expressed as median (IQR). Multivariate analysis (binary logistic regression-BLR) was conducted, adjusting for age, gender, and comorbidities besides factors significant in univariate analysis. 43 patients with IIM [31 females; age 36 (23-45) years; disease duration 5.5 (2-12) months] were enrolled for participation. DM (44%) was the most common diagnosis. IIM patients exhibited frequent attenuation of retinal vessels (32.6 vs. 4.3%, p < 0.001), AV nicking (14 vs. 2.2%, p = 0.053), and vascular tortuosity (18.6 vs. 2.2%, p = 0.012), besides decreased visual acuity (53.5 vs. 10.9%, p<0.001) and immature cataracts (34.9 vs. 2.2%, p < 0.001). Attenuation of vessels [OR 10.9 (1.7-71), p = 0.004] emerged as significantly different from HC after adjusting for covariates in BLR. Notably, adults with IIM were more predisposed to retinal abnormalities [21 (57%) vs. 1 (16%), p = 0.068], especially attenuation of vessels [14(38%) vs. 0(0), p = 0.067] than jIIM. However, no difference was found in retinal features amongst the subtypes of adult IIM, nor did they correlate with MDAAT, MDI, or HAQ-DI. Retinal microvasculopathy and diminution of vision occur in nearly one-thirds to half of the patients with IIM. Microvasculopathy occurs across subtypes of IIM, and more so in adults, calling for further investigation as a surrogate for damage assessment and potentially even systemic vascular health.

Juvenile idiopathic inflammatory myopathies: results of an open single-center retrospective study

Juvenile idiopathic inflammatory myopathies (JIIM) are rare diseases in which the prognosis is largely determined by timely diagnosis, timing of prescription and effectiveness of therapy.Objective: to characterize the clinical phenotypes, the results of paraclinical examination methods, the spectrum of autoantibodies, as well as therapeutic options in patients with JIIM.Patients and methods. The retrospective study included 37 patients with JIIM hospitalized in the pediatric department of the V.A. Nasonova Research Institute of Rheumatology from 2016 to 2020. All patients underwent a standard clinical and laboratory-instrumental examination in accordance with the diagnosis and severity of the condition.Results and discussion. Twenty-three of the 37 JIIM patients had juvenile dermatomyositis (JDM), 1 had polymyositis, and 13 had overlap-myositis (OM). The ratio of boys and girls was 1:1.7. The median age of onset for JDM was 6.9 years, and OM was 11.3 years. All patients had skeletal muscles involvement, dysphagia was detected in 52.2% of cases of JDM and in 15.4% of cases of OM. An increase in the level of creatine phosphokinase at the time of diagnosis was observed in 72.9% of patients, of lactate dehydrogenase – in 81.1%, of alanine aminotransferase - in 67.6%, of aspartate aminotransferase – in 75.7%. Heliotrope rash and/or Gottron's syndrome were observed in 100% of patients with JDM and in 30.8% with OM. Lung involvement was found in 27% of children. The myopathic capillaroscopic changes were present in 95.2% of patients with JDM and 53.8% with OM. Myositis-specific autoantibodies were found in 10.8% of patients with JIIM.All patients received glucocorticoids, 81.0% methotrexate, 18.9% hydroxychloroquine, 8.1% cyclophosphamide, 8.1% cyclosporine, 2.7% mycophenolate mofetil, 2.7% azathioprine, 67.6% - intravenous immunoglobulin. Biologic disease modifying antirheumatic drugs (bDMARDs) were prescribed to 26% of patients with JDM and to all patients with OM (only in 51.3% of cases with JIIM). The median duration of illness before initiation of bDMARDs therapy was 2.25 years. 58.8% of patients were treated with rituximab (RTM), 41.2% with abatacept (ABA). In 1 patient with OM, represented by a combination of systemic lupus erythematosus and JDM, three bDMARDs were used sequentially: ABA, etanercept and RTM. All patients achieved inactive disease status.Conclusion. JDM is the most common phenotype of JIIM, which is characterized by an earlier age of onset, skin involvement that precedes the development of myopathy, and typical capillaroscopic changes. The conclusion was made about the high efficacy and acceptable safety profile of bDMARDs therapy in children with JIIM, with careful monitoring of its tolerability. bDMARDs can be prescribed even in the early stages of the disease in the presence of unfavorable prognostic factors.

Anti-FHL1 autoantibodies in juvenile myositis are associated with anti-Ro52 autoantibodies but not with severe disease features.

Four-and-a-half LIM domains 1 (FHL1) is a muscle-specific protein. Autoantibodies against FHL1 were recently discovered in adults with idiopathic inflammatory myopathies (IIMs) and were found to be associated with clinical features and outcomes indicative of increased disease severity. Anti-FHL1 autoantibodies have not been described in children. Here, the prevalence and clinical features associated with anti-FHL1 autoantibodies were examined in a large North American cohort of juvenile patients with IIM. Sera from 338 juvenile IIM patients and 91 juvenile healthy controls were screened for anti-FHL1 autoantibodies by ELISA. Clinical characteristics and HLA alleles of those with and without anti-FHL1 autoantibodies were compared among those with juvenile IIM. Anti-FHL1 autoantibodies were present in 10.9% of juvenile IIM patients and 1.1% of controls. The frequency of anti-FHL1 autoantibodies among clinical and serologic subgroups did not differ. A higher percentage of Asian patients had anti-FHL1 autoantibodies (11% vs 0.7%; P = 0.002). Myositis-associated autoantibodies (MAAs) [odds ratio (OR) 2.09 (CI 1.03, 4.32)], anti-Ro52 autoantibodies specifically [OR 4.17 (CI 1.83, 9.37)] and V-sign rash [OR 2.59 (CI 1.22, 5.40)] were associated with anti-FHL1 autoantibodies. There were no differences in other features or markers of disease severity. No HLA associations with anti-FHL1 autoantibodies in Caucasian myositis patients were identified. Anti-FHL1 autoantibodies are present in ∼11% of juvenile IIM patients and commonly co-occur with MAAs, including anti-Ro52 autoantibodies. In contrast to adult IIM, anti-FHL1 autoantibodies in juvenile myositis are associated with V-sign rash but not with other distinctive clinical features or worse outcomes.

Experience with the use of mycophenolate mofetil in juvenile idiopathic inflammatory myopathies.

The objective of this study was to evaluate the efficacy and safety of MMF in juvenile idiopathic inflammatory myopathies (JIIMs). Patients diagnosed with JIIM and treated with MMF enrolled in the Juvenile Dermatomyositis Research Group (JDRG) in the UK or followed at the Giannina Gaslini Institute in Genoa, Italy, were included. The following information was collected retrospectively at MMF initiation, at 3, 6 and 12 months after treatment start, and at last follow-up visit: clinical manifestations, laboratory data, physicians' subjective assessment of disease activity, standardized outcome measures of muscle strength/endurance, cutaneous disease activity, physical function, global disease activity, cumulative damage, and ongoing treatment. Of the 29 patients included, 23 had juvenile DM and 6 had overlap myositis. During administration of MMF, improvement in measures of muscle strength, skin disease activity, and overall disease activity was seen, with an increase in the frequency of normal scores for Manual Muscle Test-8 from 50.0% to 83.3%, Childhood Myositis Activity Score from 53.5% to 88.9%, muscle component of DAS from 55.2% to 84.2%, skin component of DAS from 31.0% to 42.1%, visual analogue scale for skin disease activity from 25.0% to 47.4%, and visual analogue scale for overall disease activity from 7.1% to 42.1%. The number of patients with inactive disease increased from 10.3% at baseline to 68.5% at last follow-up. CS dose was significantly reduced, from 0.3 to 0.1 mg/kg/day. No relevant side effects were reported. Our experience suggests that MMF is a valuable therapeutic option for the management of JIIM.

Performance of the 2017 European Alliance of Associations for Rheumatology/American College of Rheumatology Classification Criteria in Patients With Idiopathic Inflammatory Myopathy and Anti-Melanoma Differentiation-Associated Protein 5 Positivity.

This study aimed to evaluate whether the 2017 European Alliance of Associations for Rheumatology (EULAR)/American College of Rheumatology (ACR) classification criteria for adult and juvenile idiopathic inflammatory myopathies (IIMs) could appropriately classify the diagnosis in adult patients with anti-melanoma differentiation-associated protein 5 (anti-MDA-5)-positive IIM. In addition, this study sought to determine whether a status of anti-MDA-5 positivity could be incorporated into the EULAR/ACR IIM classification criteria set and whether the recently modified criteria based on the presence of myositis-specific autoantibodies (MSAs) could be used to appropriately classify the diagnosis in patients with anti-MDA-5-positive IIM. Consecutive adult patients clinically diagnosed as having anti-MDA-5-positive IIM from 10 hospitals in Hong Kong were retrospectively recruited; patient characteristics were obtained from electronic medical records. We used a commercial line blot immunoassay to detect MSAs. We also determined a proposed set of phenotypic-serologic classification criteria specific for anti-MDA-5. In the patient cohort (n=120; 31.7% with dermatomyositis, 68.3% with clinically amyopathic dermatomyositis [CADM]), the diagnosis could be classified with the EULAR/ACR criteria in 86 patients (71.7%) and with the Bohan and Peter criteria in 49 patients (40.8%). However, when combined with criteria specifically modified for CADM, the diagnosis could be classified by the Bohan and Peter criteria in 76.7% of patients. We observed that the sensitivity of the EULAR/ACR criteria could be improved to 98.3% if anti-MDA-5 antibody-positive status was considered as one of the criteria. The MSA-based criteria had 100% sensitivity. When we applied our proposed specific phenotypic-serologic criteria for the classification of patients with anti-MDA-5 antibodies, 97.5% of patients were able to be classified as having IIM. In this cohort of patients with anti-MDA-5-positive IIM, the diagnosis could not be classified by the EULAR/ACR criteria in almost 30% of patients. We suggest incorporating anti-MDA-5 antibody positivity as a criterion into existing criteria sets or developing specific criteria for patients with anti-MDA-5-positive IIM.

Evaluation of the European League Against Rheumatism/American College of Rheumatology-2019 classification criteria in patients with childhood-onset systemic lupus erythematosus: a single-center retrospective study.

This study aimed to compare the sensitivity and specificity of the European League Against Rheumatism/American College of Rheumatology-2019 (EULAR/ACR-2019) classification criteria with prior classification schemes for patients with childhood-onset systemic lupus erythematosus (cSLE). This single-center retrospective study examined 53 patients with cSLE and 53 patients having antinuclear antibody (ANA) titers ≥ 1:80 but not cSLE as controls. Sensitivity and specificity were calculated for the EULAR/ACR-2019 criteria, original criteria reported earlier in 2019, the ACR-1997 criteria, and the Systemic Lupus International Collaborating Clinics-2012 (SLICC-2012) criteria. The frequency of positivity in the cSLE group for each item of the EULAR/ACR-2019, ACR-1997, and SLICC-2012 criteria was determined. Characteristics of the misclassified patients were also investigated. All patients with cSLE had ANA titers ≥ 1:80. The non-SLE diagnoses included juvenile idiopathic inflammatory myopathies, primary Sjögren's syndrome (pSS), juvenile idiopathic arthritis, systemic sclerosis, mixed connective tissue disease (MCTD), and others. Sensitivities of the EULAR/ACR-2019 criteria, the original criteria, the ACR-1997 criteria, and the SLICC-2012 criteria were 100%, 100%, 86.8%, and 100%, respectively; the specificities were 84.9%, 92.5%, 98.1%, and 88.7%, respectively. In the cSLE group, the items of the SLE-specific antibody (100%), complement (98.1%), hematological (94.3%), and renal (84.9%) domains were frequently observed in the EULAR/ACR-2019 criteria. The EULAR/ACR-2019 criteria misclassified patient controls more frequently, especially those with MCTD or pSS, as having SLE than the previous criteria. The EULAR/ACR-2019 criteria for cSLE had high sensitivity but low specificity; the weighted scoring of the original criteria reported earlier in 2019 may confer higher specificity and be more appropriate for the classification of SLE in a pediatric population. Key Points • The EULAR/ACR-2019 criteria for cSLE had high sensitivity but low specificity. • The EULAR/ACR-2019 criteria more frequently misclassified non-SLE patients who did not have SLE, especially those with MCTD or pSS, as having SLE than the previous criteria in patients with childhood onset. • The weighted scoring of the original criteria reported earlier in 2019 may confer higher specificity and be a more appropriate classification of SLE for a pediatric population.

Periorbital rash and scaly plaques in a 13-year–old boy

Periorbital rash and scaly plaques in a 13-year–old boy

A systematic review on biological therapies in juvenile idiopathic inflammatory myopathies: an evidence gap in precision medicine.

Juvenile idiopathic inflammatory myopathies (JIIMs) are a heterogeneous group of systemic autoimmune diseases. Juvenile dermatomyositis (JDM) is the predominant form of JIIMs, and is a rare, chronic autoimmune illness characterised by symmetric, proximal muscle damages and involvement of the skin. In the last two decades, the use of monoclonal antibodies has also been expanded to JIIMs; however, there is limited evidence on use of these treatments. We assessed the efficacy/effectiveness and safety of biologic agents in JIIMs. A systematic literature review was conducted using Embase®, MEDLINE®, MEDLINE®-In Process and Cochrane library to identify studies on biologics agents in JIIMs published in English language as full-text articles (1975 to December 2020) or conference abstracts (2000 to December 2020). Databases were searched with the key words regarding chronic myositis crossed with "biologic agents OR tocilizumab OR rituximab OR adalimumab OR infliximab OR anti-TNF OR etanercept". Of note, we did not include children, age, or age limits in the search as medical subject headings terms because we may have been able to extract a sub cohort of children from studies including both children and adults. Of the 1633 retrieved publications, 18 articles were identified for a total of 165 patients. In real-world studies, definition of complete (CR) or partial response (PR) varied. JIIMs patients were most often treated with anti-TNF (88 pts); patients received etanercept (ETA), 48 patients infliximab (IFX), 4 patients received adalimumab (ADA). In other 15 patients IFX was followed by ADA. Rituximab (RTX) was used in 73 children. A single case series reported the use of abatacept (ABA) in 4 patients. Despite the reduced number of treated patients, complete response on myositis was reported in 29.6% (8/26) patients treated with at least one anti-TNF and in 38% (10/26) treated by RTX. Complete response of skin vasculitis has been reached in 33% (4/12) children on anti-TNF and in 36% on RTX (21/58). Anti-TNF agents might be efficient in treating calcinosis lesions. Currently, the available evidence regarding the use of biologic treatment in JIIMs results quite limited but suggest a promising the use of anti-TNF agents and RTX in treating active JIIMs. Anti-TNF treatment might have a role in treating calcinosis. However, an overall very low quality of the available studies and multiple confounding factors hamper to suggest a treatment over another. Thus, randomised clinical trials are urgently required to attempt the optimal treatment in real-world setting.

Morphological Characteristics of Idiopathic Inflammatory Myopathies in Juvenile Patients.

Background: In juvenile idiopathic inflammatory myopathies (IIMs), morphological characteristic features of distinct subgroups are not well defined. New treatment strategies require a precise diagnosis of the subgroups in IIM, and, therefore, knowledge about the pathomorphology of juvenile IIMs is warranted. Methods: Muscle biopsies from 15 patients (median age 8 (range 3–17) years, 73% female) with IIM and seven controls were analyzed by standard methods, immunohistochemistry, and transmission electron microscopy (TEM). Detailed clinical and laboratory data were accessed retrospectively. Results: Proximal muscle weakness and skin symptoms were the main clinical symptoms. Dermatomyositis (DM) was diagnosed in 9/15, antisynthetase syndrome (ASyS) in 4/15, and overlap myositis (OM) in 2/15. Analysis of skeletal muscle tissues showed inflammatory cells and diffuse upregulation of MHC class I in all subtypes. Morphological key findings were COX-deficient fibers as a striking pathology in DM and perimysial alkaline phosphatase positivity in anti-Jo-1-ASyS. Vascular staining of the type 1 IFN-surrogate marker, MxA, correlated with endothelial tubuloreticular inclusions in both groups. None of these specific morphological findings were present in anti-PL7-ASyS or OM patients. Conclusions: Morphological characteristics discriminate IIM subtypes in juvenile patients, emphasizing differences in aetiopathogenesis and supporting the notion of individual and targeted therapeutic strategies.

Development and Preliminary Validation of an Electromyography-Scoring Protocol for the Assessment and Grading of Muscle Involvement in Patients With Juvenile Idiopathic Inflammatory Myopathies

IntroductionWe performed a pilot study in order to investigate the feasibility of an electromyography (EMG)-scoring protocol for the assessment of disease activity in juvenile idiopathic inflammatory myopathies (JIIM). MethodsChildren with JIIM followed up in a tertiary-level care center underwent standardized clinical, laboratory, and EMG assessment. An EMG-scoring protocol was devised by a consensus panel including a pediatric neurophysiologist and two pediatric rheumatologists, based on a combined score obtained as the sum of (1) the presence of denervation signs (fibrillation potentials) and (2) motor unit remodeling (mixed pattern of short- and long-duration motor unit action potentials). The EMG-scoring protocol was then validated following the Outcome Measures in Rheumatoid Arthritis Clinical Trials filter for outcome measures in rheumatology and the consensus-based standards for the selection of health measurement instruments methodology. ResultsThirteen children (77% females) were included in the study, with a median age of 10 years (interquartile range: 7-17 years) and median disease duration of 11.8 months (interquartile range: 2.1-44.5). A total of 39 EMG examinations were evaluated. A strong positive association between a standardized tool for muscle strength assessment and the combined score was observed. No significant associations were found with both creatine kinase and erythrocyte sedimentation rate levels. DiscussionOur EMG-scoring protocol is the first standardized and reproducible tool for the neurophysiologic evaluation and grading of muscle involvement in patients with JIIM and could provide relevant additional information in the assessment and follow-up of these rare conditions.

Juvenile idiopathic inflammatory myopathies with anti-3-hydroxy-3-methylglutaryl-coenzyme A reductase antibodies in a Chinese cohort.

AimsTo characterize the clinical and histopathological characteristics and treatment outcomes of juvenile idiopathic inflammatory myopathies (JIIMs) with anti‐3‐hydroxy‐3‐methylglutaryl‐coenzyme A reductase (HMGCR) antibodies in a Chinese cohort.MethodsWe detected anti‐HMGCR antibodies in a series of Chinese JIIM by ELISA and indirect immunofluorescence assay on HEK293 cells, and summarized the clinical findings of these anti‐HMGCR antibody‐positive patients.ResultsOf 32 JIIM patients, 5 (15.63%) were found to be anti‐HMGCR antibody‐positive. The disease duration was 1.20 ± 0.45 months. Statin exposure was not found. Four patients had skin lesions, while typical pathological features of dermatomyositis such as perifascicular atrophy or myxovirus resistance protein A expression were not found. The mean creatine kinase level was 16771.60 U/L. Among the four patients who received long‐term (10.46 ± 1.42 years) follow‐up, three exhibited favorable outcomes with prednisone and additional immunosuppressants.ConclusionsOur study indicates that anti‐HMGCR antibodies may not be rare in Chinese JIIM. These anti‐HMGCR‐positive JIIMs were characterized by acute onset, substantially elevated creatine kinase level, and skin lesions without perifascicular changes in muscle pathology. The treatment outcome is generally favorable with the combination of steroid and immunosuppressant.

Use of Rescue Therapy with IVIG or Cyclophosphamide in Juvenile Myositis.

This review aims to present the literature available to date on the use of intravenous immunoglobulin and cyclophosphamide for juvenile patients with inflammatory myopathies, to evaluate the strength of the evidence so far for both these medications, and to reach conclusions about their efficacy. Juvenile idiopathic inflammatory myopathies, mainly represented by juvenile dermatomyositis (JDM), are rare diseases but quite debilitating for the patients. JDM is an autoimmune condition with predominantly muscle and skin involvement but also systemic features affecting the cardiovascular, respiratory, and gastrointestinal systems. The mainstay therapy is based on corticosteroids and methotrexate, but often other therapeutic alternatives are sought for patients with severe or refractory disease. The rarity of these conditions makes research for new medications even more challenging. Innovative trial designs or statistical methods can be used to emulate a randomized study and investigate drug effectiveness. Despite the lack of Level I evidence on the use and efficacy of intravenous immunoglobulin and cyclophosphamide, their use is advocated by a substantial number of case reports and case series as well as analyses using marginal structural models.

Clinical impact of myositis-specific autoantibodies on long-term prognosis of juvenile idiopathic inflammatory myopathies: multicentre study.

This study aimed to investigate the clinical characteristics, treatment and prognosis of juvenile idiopathic inflammatory myopathies (JIIM) in Japan for each myositis-specific autoantibody (MSA) profile. A multicentre, retrospective study was conducted using data of patients with JIIM at nine paediatric rheumatology centres in Japan. Patients with MSA profiles, determined by immunoprecipitation using stored serum from the active stage, were included. MSA were detected in 85 of 96 cases eligible for the analyses. Over 90% of the patients in this study had one of the following three MSA types: anti-melanoma differentiation-associated protein 5 (MDA5) (n = 31), anti-transcriptional intermediary factor 1 alpha and/or gamma subunits (TIF1γ) (n = 25) and anti-nuclear matrix protein 2 (NXP2) (n = 25) antibodies. Gottron papules and periungual capillary abnormalities were the most common signs of every MSA group in the initial phase. The presence of interstitial lung disease (ILD) was the highest risk factor for patients with anti-MDA5 antibodies. Most patients were administered multiple drug therapies: glucocorticoids and MTX were administered to patients with anti-TIF1γ or anti-NXP2 antibodies. Half of the patients with anti-MDA5 antibodies received more than three medications including i.v. CYC, especially patients with ILD. Patients with anti-MDA5 antibodies were more likely to achieve drug-free remission (29 vs 21%) and less likely to relapse (26 vs 44%) than others. Anti-MDA5 antibodies are the most common MSA type in Japan, and patients with this antibody are characterized by ILD at onset, multiple medications including i.v. CYC, drug-free remission, and a lower frequency of relapse. New therapeutic strategies are required for other MSA types.