Classification Of Myositis Research Articles

12O Clinical, paraclinical features and classification of myositis in Viet Nam

12O Clinical, paraclinical features and classification of myositis in Viet Nam

Current efforts and historical perspectives on classification of idiopathic inflammatory myopathies.

The classification of idiopathic inflammatory myopathies is challenging due to the large number of clinical, serological, histopathological and genetic findings, as well as the latest findings and developments in the field of myositis research. The latest official classification criteria are the 2017 European Alliance of Associations for Rheumatology (EULAR)/American College of Rheumatology (ACR) classification criteria for adult and juvenile idiopathic inflammatory myopathies, which have been extensively reviewed in recent years for their applicability, sensitivity and specificity. The sensitivity and specificity of the 2017 ACR/EULAR criteria are sometimes performing better, but usually at the same level as the previous criteria. A large number of further suggestions for amendments to the criteria have been made. In particular there is a need to revise the criteria with regard to the addition of new myositis-specific autoantibodies, newly defined subgroups (especially antisynthetase syndrome, immune medicated necrotizing myopathy and overlap myositis) and possibly the addition of further diagnostic procedures (for instance, muscle MRI or PET CT) to improve the accuracy and timeliness of the criteria. Efforts to optimize the myositis classification criteria have been extensive in recent years and a new global interdisciplinary collaboration of clinicians is currently taking place based on the previous results with the aim of revising the 2017 EULAR/ACR classification criteria.

MGB-Unet: An Improved Multiscale Unet with Bottleneck Transformer for Myositis Segmentation from Ultrasound Images.

Myositis is the inflammation of the muscles that can arise from various sources with diverse symptoms and require different treatments. For treatment to achieve optimal results, it is essential to obtain an accurate diagnosis promptly. This paper presents a new supervised segmentation architecture that can efficiently perform precise segmentation and classification of myositis from ultrasound images with few computational resources. The architecture of our model includes a unique encoder-decoder structure that integrates the Bottleneck Transformer (BOT) with a newly developed Residual block named Multi-Conv Ghost switchable bottleneck Residual Block (MCG_RB). This block effectively captures and analyzes ultrasound image input inside the encoder segment at several resolutions. Moreover, the BOT module is a transformer-style attention module designed to bridge the feature gap between the encoding and decoding stages. Furthermore, multi-level features are retrieved using the MCG-RB module, which combines multi-convolution with ghost switchable residual connections of convolutions for both the encoding and decoding stages. The suggested method attains state-of-the-art performance on a benchmark set of myositis ultrasound images across all parameters, including accuracy, precision, recall, dice coefficient, and Jaccard index. Despite its limited training data, the suggested approach demonstrates remarkable generalizability by yielding exceptional results. The proposed model showed a substantial enhancement in accuracy when compared to segmentation state-of-the-art methods such as Unet++, DeepLabV3, and the Duck-Net. The dice coefficient and Jaccard index obtained improvements of up to 3%, 6%, and 7%, respectively, surpassing the other methods.

The impact of pain on daily activities in patients with idiopathic inflammatory myopathies: Report from the OMERACT myositis working group

BackgroundInternational focus groups with patients with idiopathic inflammatory myopathies (IIM) conducted by the OMERACT Myositis Working Group over the years demonstrated the pain as an important symptom experienced by these patients. In this study, we aimed to examine the frequency and degree of pain interference, the aspects of daily life impacted by pain, and the factors associated with pain interference in adults with IIM. MethodsThis was a prospective observational study with two visits. The patients who fulfilled the probable/definite IIM (ACR/EULAR Myositis Classification Criteria) were enrolled. Pain interference was assessed with PROMIS pain interference form (6a). Myositis core set measures and PROMIS fatigue (7a) and physical function (8b) were obtained at both visits. Logistic regression and linear mixed models were performed to assess the association between pain interference and other parameters. ResultsA total of 129 patients with IIM (60 % females) were recruited from U.S., South Korea, Netherlands, Sweden, and Australia. Approximately 71 % reported pain interference. The patients in the greater pain interference group were more likely to be female, had significantly worse patient/physician global disease activity, fatigue, and physical function than those in the lower pain interference group. The most commonly impacted life aspect was household chores. Manual muscle testing, patient/physician global disease activity, fatigue, and physical function were all significantly associated with pain interference score >60. ConclusionThe majority of the patients with IIM experience the impact of pain on their daily activities, particularly household chores. Myositis disease activity, duration, and subtype could be associated with greater pain interference.

Neuropathology I: muscular diseases

Muscle diseases include hereditary and acquired diseases with clinical manifestation in both childhood and adulthood. The different muscle diseases may have ultrastructural alterations that help us further understand the pathology of the disease. Specific changes in sarcomere structure help to classify acongenital myopathy. The detection of cellular aggregates supports the classification of myositis. Pathologically altered mitochondria, on the other hand, can occur both in genetic mitochondriopathies but also secondarily in acquired muscle diseases like myositis. Ultrastructural analysis of the myocardium is also helpful in the diagnosis of hereditary cardiomyopathies in childhood. This review article highlights the ultrastructural features of different muscle diseases and pathognomonic findings in specific disease groups.

Myositis

The S2e guidelines on myositis were completely updated and revised under the leadership of the German Society for Neurology and the participation of many other specialist societies. Immune-mediated necrotizing myopathy and antisynthetase syndrome are now regarded as independent entities in the classification of myositis. With respect to the diagnostics, the guidelines provide concrete recommendations on dysphagia screening, especially for inclusion body myositis and for cancer diagnostics in certain forms of myositis. Following the positive ProDERM study, the use of intravenous immunoglobulins (Octagam®) is available for treatment as an approved substance. Based on the INBUILD study, antifibrotic treatment with nintedanib is available for progressive fibrosing pulmonary involvement. For rheumatologists, the updated guidelines represent a document relevant for daily practice with many recommendations for the treatment of patients with myositis.

Generalised idiopathic polymyositis mimicking masticatory myositis in a dog

AbstractMasticatory myositis (MM) and generalised idiopathic polymyositis (gIPM) are the most common immune‐mediated myositis in dogs. In humans, the diagnosis and classification of myositis have continuously evolved over the past few decades with the combination of histopathological and immunohistochemical evaluation alongside the identification of myositis‐specific autoantibodies (MSAs). In dogs, however, MSAs have only been described in MM and breeds such as Newfoundland and Boxer. We report a case of a dog that presented with sub‐acute pain when chewing and exophthalmos, followed by chronic progressive masticatory muscle atrophy and enophthalmos. Clinical signs and electromyography were primarily consistent with MM, but serological autoantibodies against type 2M myofibres were negative. Creatine kinase activity, histological and immunohistochemical examination of the temporal and triceps brachii muscles and negative infectious disease tests were consistent with gIPM. This atypical case highlights the requirement for multiple muscle biopsies and appeals for extended immunohistochemical studies in canine myositis.

Mortality Risk Stratification Using Cluster Analysis in Patients With Myositis-Associated Interstitial Lung Disease Receiving Initial Triple-Combination Therapy.

ObjectiveTo stratify patients with polymyositis/dermatomyositis-associated interstitial lung disease (ILD) who were initially treated with an intensive regimen consisting of high-dose corticosteroids, a calcineurin inhibitor, and intravenous cyclophosphamide (triple-combo therapy) into subgroups based on mortality outcomes by a cluster analysis using a large-scale multicenter retrospective cohort of Japanese patients with myositis-associated ILD (JAMI).MethodsTwo-step cluster analysis of preclustering and subsequent hierarchical clustering was conducted in 185 patients who received triple-combo therapy in an unbiased manner. Initial predictors for mortality previously reported in patients with myositis-associated ILD were used as variables and included age, sex, disease duration, classification of myositis, requirement of supplemental oxygen, anti-aminoacyl tRNA synthetase (ARS) antibody, anti-melanoma differentiation-associated gene 5 (MDA5) antibody, and serum levels of C-reactive protein (CRP) and Krebs von den Lungen-6 (KL-6). The cluster model was further applied to 283 patients who received conventional regimens consisting of corticosteroids with or without a single immunosuppressive agent (dual-combo therapy or monotherapy). Cumulative survival rates were compared using Kaplan-Meier analysis, and the log-rank test was used to test for significant differences between two groups.ResultsWe developed a cluster model consisting of 6 clusters, which were categorized by age at onset, clinically amyopathic dermatomyositis, CRP, KL-6, requirement of supplemental oxygen, anti-ARS antibody, and anti-MDA5 antibody. This model was judged to be of good quality based on the silhouette measure of cohesion and separation of 0.6. These clusters were regrouped into three subsets based on low (<10%), moderate (10-50%), and high (>50%) mortality rates. The performance of the clustering was generally replicated in patients who received initial dual-combo therapy or monotherapy. Survival benefits of triple-combo therapy over dual-combo therapy or monotherapy were not observed in any of the clusters.ConclusionWe successfully developed a cluster model that stratified patients with myositis-associated ILD who were treated with initial triple-combo therapy into subgroups with different prognoses, although this model failed to identify a patient subgroup that showed survival benefits from triple-combo therapy over dual-combo therapy or monotherapy.

Performance of the 2017 European Alliance of Associations for Rheumatology/American College of Rheumatology Classification Criteria for Idiopathic Inflammatory Myopathies in Patients With Myositis-Specific Autoantibodies.

We undertook this study to 1) determine the sensitivity of the European Alliance of Associations for Rheumatology (EULAR)/American College of Rheumatology (ACR) classification criteria for idiopathic inflammatory myopathies (IIMs) to properly classify myositis-specific autoantibody (MSA)-positive myositis patients, 2) describe the phenotype and muscle involvement over time in different MSA-positive patients, and 3) compare MSA subgroups to EULAR/ACR criteria-defined myositis subgroups for their capacity to predict clinical phenotypes in patients with IIMs. The study included 524 MSA-positive myositis patients from the Johns Hopkins Myositis Center. Each patient was classified using the EULAR/ACR classification criteria. Patient phenotypes were summarized using factor analysis of mixed data (FAMD). We compared the ability of MSAs to that of the EULAR/ACR classification subgroups to predict the phenotype of patients by applying the Akaike information criterion (AIC) and the Bayesian information criteria (BIC) to the linear regression models. Overall, 91% of MSA-positive patients met the EULAR/ACR criteria to be classified as having myositis. However, 20% of patients with anti-hydroxymethylglutaryl-coenzyme A reductase (anti-HMGCR) and 50% of patients with anti-PL-7 were incorrectly classified as not having myositis. Furthermore, ~10% of patients with anti-signal recognition particle (anti-SRP) and patients with anti-HMGCR were misclassified as having inclusion body myositis. FAMD demonstrated that patients within each MSA-defined subgroup had similar phenotypes. Application of both the AIC and BIC to the linear regression models revealed that MSAs were better predictors of myositis phenotypes than the subgroups defined by the EULAR/ACR criteria. Although the EULAR/ACR criteria successfully classified 91% of MSA-positive myositis patients, certain MSA-defined subgroups, including those with autoantibodies against HMGCR, SRP, and PL-7, are frequently misclassified. In myositis patients with MSAs, autoantibodies outperform the EULAR/ACR-defined myositis subgroups in predicting the clinical phenotypes of patients. These findings underscore the need to include MSAs in a revised myositis classification scheme.

Classification of myositis from muscle ultrasound images using deep learning

Inflammatory myopathies, are rare muscle diseases. As a result of the body's own immune system attacking by targeting the muscle cells, muscle weakness develops due to inflammation in the muscles. Early and definitive diagnosis of the disease is very important for treatment. In this study, it is aimed to develop a computer-aided diagnosis system that diagnoses diseases from muscle ultrasound images using deep learning methods. 3214 muscle ultrasound images of 19 inclusion body myositis, 14 polymyositis, 14 dermatomyositis and 33 normal patients were used as dataset. In the study, a new deep learning model was proposed by combining the VGG16 and VGG19 architectures which are well known in terms of classification performance. The proposed model has been tested on binary and multiple classification problems. For binary classification problems, in the first scenario (S1), normal images were examined with all disease images. In the second scenario (S2), normal images were examined with only inclusion body myositis images. In the third scenario (S3) inclusion body myositis images were examined with dermatomyositis and polymyositis images. The proposed model reached an average accuracy of 93.00% in S1, 96.01% in S2, 91.74% in S3 and 95.12% in multi-class classification (S4). The results obtained from the test dataset indicated that the proposed deep learning approach is effective in automatic classification of inflammatory myopathies.

P153 Characteristics of anti-melanoma differentiation-associated gene 5 positive dermatomyositis in Singapore

Abstract Background/Aims Anti-melanoma differentiation-associated gene 5 (MDA5) Ab positive associated dermatomyositis (DM) patients with rapidly progressive-interstitial lung disease (RP-ILD) have poor survival rates. The aim of this study was to determine the various characteristics in Singaporean patients with anti-MDA5-Ab associated DM. Methods A chart review was undertaken of 84 DM patients with positive myositis specific antibodies, diagnosed between January 2015 to July 2019, at a major tertiary centre in Singapore. All had confirmed probable or definite DM according to the Bohan and Peter criteria, and only those with an International Myositis Classification Criteria score of at least 55% (probable idiopathic inflammatory DM) were included. Results 18 out of 84 were anti-MDA5-Ab positive (See Table 1 for summary). Features more common in the anti-MDA5 Ab positive vs. the anti-MDA5 Ab negative cohort included: inverse Gottron’s papules (27.8% vs. 3%, p = 0.001) palmar papules (27.8% vs. 0%, p &amp;lt; 0.001), violaceous rash (55.6% vs. 16.7%, p = 0.001), cutaneous ulcers (66.7% vs. 6.1%, p = &amp;lt;0.001), clinically amyopathic DM (50% vs. 22.7%, p = 0.023) and polyarthritis (38.9% vs. 12.1%, p = 0.0009). The anti-MDA5 Ab positive cohort had a lower median creatine kinase (IU/L) versus the anti-MDA5 Ab negative cohort; 328 [60-3254] vs. 1318 [61-36776], (p = 0.0027). ILD was more common in the anti MDA5 Ab positive vs. anti-MDA5 Ab negative cohort (61.1% vs. 34.8%; p = 0.044). Of these anti-MDA5 Ab positive with ILD, 45.5% had RP-ILD, 27.3% had either chronic ILD or asymptomatic ILD respectively. In contrast, only 17.4% had RP-ILD in the anti-MDA5 Ab negative cohort. The mortality rate in the anti-MDA5 Ab positive vs. negative cohort was higher (33.3% vs. 24.2%). Patients with both Ro-52 and MDA5 Ab positivity had a higher incidence of cutaneous ulcers, pneumothorax, ILD and mortality. Of those anti-MDA5-Ab positive cases that survived, treatment included either rituximab and/or tofacitinib. Conclusion In our population, anti-MDA5 Abs associated DM is a distinct clinical subset of DM and associated with increased mortality. Better recognition of these distinct clinical features will enable early diagnosis, risk stratification and aggressive treatment to improve survival. Disclosure J. Low: None. C. Chua: None. W. Lim: None. L. Koh: None. M. Manghani: None.

O33 Earlier cancer diagnosis after myositis onset is associated with improved long term survival: results from UK, French and Czech cohorts

Abstract Background The idiopathic inflammatory myopathies (IIMs) are associated with cancer. Cancer screening is advocated in new IIM cases; however no study has investigated if this confers improved long-term survival. This study aimed to investigate if a shorter time between IIM onset and cancer diagnosis is associated with improved survival. Methods Verified adult-onset IIM (dermatomyositis, polymyositis, anti-synthetase syndrome) cases, according to the International Myositis Classification Criteria, were recruited from three separate UK (UKMYONET), France and Czech-based cohort studies. Only cases with cancer diagnosis following IIM onset were included in analysis. The time between IIM onset and cancer diagnosis was calculated for each case. The relationship between survival at the end of follow up and time between IIM onset and cancer diagnosis was quantified via calculation of hazard ratios using a Cox-proportional hazard model, adjusted for age and gender. Results A total of 193 (66% female) IIM cases with a total of 1,395 person-years follow up were included in the analysis (Table 1). Data of 120 UK, 45 Czech and 28 French participants were analysed. Breast was the most common site of cancer (16%), followed by lung (9%) and bowel (6%). Forty six (24%) deaths occurred within the follow up period. The IIM onset to cancer diagnosis time was shorter for those that survived at the end of follow up, compared to those that died: 4.6 years (IQR 1.2, 10.7), vs 5.8 years (IQR 1.6, 13.8), respectively. Cox-proportional hazard modelling, indicated that a longer time between IIM onset and cancer diagnosis was significantly associated with death (HR 1.06 [95% CI 1.02, 1.10]). This significant relationship was only demonstrated in the female cohort when analysed separately: female HR 1.06 (95% CI 1.01, 1.10), male HR 1.08 (95% CI 0.98, 1.18). Conclusion Using data from three international cohorts, this study has, for the first time, identified that earlier cancer diagnosis after IIM onset is associated with improved long term survival. This finding was observed in the female cohort only. This study therefore indicate that cancer screening in newly diagnosed IIM cases without a preceding cancer history should be carried out, especially in female cases. Disclosures A. Oldroyd None. P. New None. J. Lamb None. W. Ollier None. R. Cooper None. K. Mariampillai None. O. Benveniste None. J. Vencovský None. H. Mann None. H. Chinoy None.

Idiopathic inflammatory myopathy: From muscle biopsy to serology

Idiopathic inflammatory myopathies (IIMs) are heterogeneous group of muscle disorders characterized by variable degree of muscle weakness and muscle inflammation. Various classification systems have been proposed for myositis. However, there remains a diagnostic uncertainty due to the presence of overlapping clinical and pathological features. Similar treatment outcomes to immunosuppressant drugs further add to diagnostic confusion. Introduction of myositis-specific and myositis-associated autoantibodies has widened the disease spectrum of IIMs. Despite being very crucial for the diagnosis and classification of myositis, these autoantibodies are not always present. Therefore, histopathological features and immunohistochemical markers are considered gold standard for the diagnosis of myositis. A correct diagnosis has important clinical and therapeutic implications. In this review, we have focused on salient clinicopathological features and newly developed serological markers in major subtypes of IIMs.

External Validation and Evaluation of Adding MRI or Extended Myositis Antibody Panel to the 2017 EULAR/ACR Myositis Classification Criteria.

ObjectiveTo externally validate the European League Against Rheumatism/American College of Rheumatism (EULAR/ACR) classification criteria for idiopathic inflammatory myositis (IIM) and determine the optimal cut points for Australian patients. To determine the level of agreement with traditional criteria and assess the effect of including magnetic resonance imaging (MRI) and an extended myositis antibody panel as well as extending histological criteria to include myofiber invasion.MethodsData were collected on adult patients referred for muscle biopsy to two Australian teaching hospitals. Patients were scored for “risk of IIM” according to EULAR/ACR criteria, using clinician diagnosis as the gold standard.ResultsOverall, 87 of 204 patients had IIM. For patients with muscle biopsy, the optimal cut point of 5.25 (sensitivity 90%, specificity 89%) was lower than the EULAR/ACR cut point of 6.7, which in our cohort showed reduced sensitivity (71% vs 93%) but comparable specificity (89% vs 88%). We found moderate agreement between the EULAR/ACR criteria and Bohan and Peter (κ = 0.45, 95% confidence interval [CI] = 0.28, 0.62, P < 0.001) and Targoff (κ = 0.40, 95% CI = 0.23, 0.57, P < 0.001). Inclusion of MRI (area under curve [AUC] = 0.86, 95% CI = 0.79, 0.93) or non‐Jo1 antibodies (AUC = 0.84, 95% CI = 0.77, 0.91) as covariates improved the probability of IIM diagnosis (AUC = 0.80, 95% CI = 0.75, 0.86). Extending histologic criteria to include myofiber invasion slightly improved sensitivity (75% vs 71%) with the same level of specificity (89% vs 89%).ConclusionApplication of the EULAR/ACR criteria to an Australian cohort showed comparable specificity but lower sensitivity, and a lower optimal cut point. Inclusion of MRI or non‐Jo1 antibodies as covariates may improve the accuracy of determining the probability of IIM diagnoses. Extending the histologic criteria to include myofiber invasion did not reduce specificity.

Strategy for suspected myositis.

Skeletal muscle inflammation is the feature shared by all forms of myositis. However, the muscle damage ranges in severity from asymptomatic to responsible for severe weakness. In addition, myositis usually occurs as a systemic disease that affects multiple organs. More specifically myositis should be considered in patients with muscular, cutaneous, pulmonary, and articular manifestations. The definitive diagnosis and classification of myositis has benefited considerably in recent years from the identification of characteristic autoantibodies. Nonetheless, a muscle biopsy is often necessary to confirm the diagnosis, and the differential diagnoses may raise challenges that require evaluation at a myositis referral center. The management depends on the type of myositis. Treatments should be provided for both the systemic complications (involving the lungs, heart, gastrointestinal tract, and/or joints) and the comorbidities (cancer and risks factors for cardiovascular disease, thromboembolism, and fractures), which together determine the prognosis. Many drugs are available for treating myositis. Findings from randomized controlled trials will help to use them optimally.

Classification of myositis.

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.

Integrated classification of inflammatory myopathies.

Inflammatory myopathies comprise a multitude of diverse diseases, most often occurring in complex clinical settings. To ensure accurate diagnosis, multidisciplinary expertise is required. Here, we propose a comprehensive myositis classification that incorporates clinical, morphological and molecular data as well as autoantibody profile. This review focuses on recent advances in myositis research, in particular, the correlation between autoantibodies and morphological or clinical phenotypes that can be used as the basis for an 'integrated' classification system.

Modern Therapies for Idiopathic Inflammatory Myopathies (IIMs): Role of Biologics.

Despite the lack of placebo-controlled trials, glucocorticoids are considered the mainstay of initial treatment for idiopathic inflammatory myopathy (IIMs) and myositis-associated ILD (MA-ILD). Glucocorticoid-sparing agents are often given concomitantly with other immunosuppressive agents, particularly in patients with moderate or severe disease. As treatment of refractory cases of idiopathic inflammatory myopathies has been challenging, there is growing interest in evaluating newer therapies including biologics that target various pathways involved in the pathogenesis of IIMs. In a large clinical trial of rituximab in adult and juvenile myositis, the primary outcome was not met, but the definition of improvement was met by most of this refractory group of myositis patients. Rituximab use was also associated with a significant glucocorticoid-sparing effect. Intravenous immune globulin (IVIg) can be used for refractory IIMs or those with severe dysphagia or concomitant infections. Anti-tumor necrosis factor (anti-TNF) utility in IIMs is generally limited by previous negative studies along with recent reports suggesting their potential for inducing myositis. Further research is required to assess the role of new therapies such as tocilizumab (anti-IL6), ACTH gel, sifalimumab (anti-IFNα), and abatacept (inhibition of T cell co-stimulation) given their biological plausibility and encouraging small case series results. Other potential novel therapies include alemtuzumab (a humanized monoclonal antibody which binds CD52 on B and T lymphocytes), fingolimod (a sphingosine 1-phosphate receptor modulator that traps T lymphocytes in the lymphoid organs), eculizumab, and basiliximab. The future investigations in IIMs will depend on well-designed controlled clinical trials using validated consensus core set measures and improvements in myositis classification schemes based on serologic and histopathologic features.

I.I.7 - Contribution of myopathological analysis to myositis classification in a multidisciplinary approach

Diagnosis of inflammatory myopathies is based on evaluation of a certain clinical syndrome, laboratory results, electromyography and the myopathological assessment of a muscle biopsy. Recently, several additional parameters have been taken into consideration; among these, serological auto-antibody testing is the most relevant. The current classification of inflammatory myopathies (IIMs) comprises polymyositis (PM), dermatomyositis (DM), immune-mediated necrotizing myopathy (IMNM), sporadic inclusion body myositis (sIBM), and non-specific myositis (NSM). This classification has been a subject of intense critique at various levels. First, the entity of polymyositis has been questioned, since many of these patients developed either sIBM later on, or should better be grouped among the IMNM group or the NSM/overlap myositis group. Second, dermatomyositis encompasses a multitude of subgroups with different clinical, therapeutical and prognostic implications. It has been shown recently that certain subgroups can be defined by different myositis specific auto-antibodies, such as TIF1γ, Mi-2, NXP2 or MDA-5. Anti-TIF1γ+ and NXP2+ adult patients show an increased risk of systemic malignancy, while anti-Mi-2+ patients harbour a classical dermatomyositis with good response to treatment, and NXP2+ juvenile DM patients have a strongly increased risk of developing calcinosis. The morphology and in situ immune mechanisms of the skeletal muscle of these subentities are presented. Third, necrotizing myopathy was recently added to the IIMs; however, IMNM still comprises a heterogeneous group of diseases. Recently interesting advances have been achieved, illuminating the immunopathogenesis from anti-SRP+, anti-HMGCR+ patients and anti-synthetase syndrome-associated myositis. These entities will be discussed in the light of clinical, serological, morphological and immunological characteristics.

Progress report on development of classification criteria for adult and juvenile idiopathic inflammatory myopathies

Classification criteria are needed to aid recruitment of appropriate patients into research studies. The International Myositis Classification Criteria Project (IMCCP) was set up with support from ACR and EULAR.