A new proposal for phenotypic classification and outcome assessment of dermatomyositis based on clinical manifestations and serological testing.

BACKGROUND: Dermatomyositis (DM) is an infrequent disease subgroup of idiopathic inflammatory myopathies characterized by distinct skin lesions. However, high heterogeneity makes clinical diagnosis and treatment of DM very challenging. OBJECTIVES: Unsupervised classification in DM patients and analysis of key factors related to clinical outcomes. METHODS: This retrospective study was conducted between 2017 and 2022 at the Department of Rheumatology, Xiangya Hospital, Central South University. 162 DM patients were enrolled for unsupervised hierarchical cluster analysis. In addition, we divided the clinical outcomes of DM patients into four subgroups: withdrawal, stabilization, aggravation, and death, and compared the clinical profiles amongst the subgroups. RESULTS: Out of 162 DM patients, three clusters were defined. Cluster 1 (n = 40) was mainly grouped by patients with prominent muscular involvement and mild Interstitial Lung Disease (ILD). Cluster 2 (n = 72) grouped patients with skin rash, anti-Melanoma Differentiation Associated protein 5 positive (anti-MDA5+), and Rapid Progressive Interstitial Lung Disease (RP-ILD). Cluster 3 (n = 50) grouped patients with the mildest symptoms. The proportion of death increased across the three clusters (cluster 3 < cluster 1 < cluster 2). STUDY LIMITATIONS: The number of cases was limited for the subsequent construction and validation of predictive models. We did not review all skin symptoms or pathological changes in detail. CONCLUSIONS: We reclassified DM into three clusters with different risks for poor outcome based on diverse clinical profiles. Clinical serological testing and cluster analysis are necessary to help clinicians evaluate patients during follow-up and conduct phenotype-based personalized care in DM.

Association between clinical phenotypes of dermatomyositis and polymyositis with myositis-specific antibodies and overlap systemic autoimmune diseases.

ABSTRACT: The aim of this study was to evaluate the association between clinical phenotypes of dermatomyositis (DM) and polymyositis (PM) with myositis-specific antibodies (MSAs), and overlap diagnosis of systemic autoimmune diseases.This cross-sectional study was conducted on 67 patients with DM and 27 patients with PM recruited from a regional hospital in southern Taiwan. Clinical phenotypes of DM and PM were assessed and MSAs were measured using a commercial line blot assay. The association of clinical phenotypes of DM and PM with MSAs and overlap diagnosis of systemic autoimmune diseases was performed using univariate and multiple logistic regression analyses.Clinically, patients with DM and PM and overlap diagnosis of systemic sclerosis were associated with a higher risk of interstitial lung diseases (ILDs) (odds ratio [OR] = 6.73; P = .048), Raynaud phenomenon (OR = 7.30; P = .034), and malignancy (OR = 350.77; P = .013). The risk of malignancy was also associated with older age (OR 1.31; P = .012), and male patients were associated with a higher risk of fever. For MSAs, anti-aminoacyl-tRNA synthetase antibodies were associated with ILD, antinuclear antibody were associated with a lower risk of arthritis, anti-transcription intermediary factor 1-gamma antibodies were associated with milder symptoms of muscle weakness, anti-Ku antibodies were associated with overlap diagnosis of systemic lupus erythematosus, and anti-Ro52 antibodies were associated with the development of Raynaud phenomenon and Sjögren syndrome.MSAs and overlap diagnosis of systemic sclerosis were significantly associated with clinical phenotypes of DM and PM. Physicians should be vigilant for malignancy in older DM and PM patients with overlap diagnosis of systeic sclerosis. The possibility of developing ILD in patients with overlap diagnosis of systemic sclerosis or serum positivity of anti-aminoacyl-tRNA synthetase antibodies should be considered.

Identification and prediction of novel classes of long-term disease trajectories for patients with juvenile dermatomyositis using growth mixture models.

OBJECTIVES: Uncertainty around clinical heterogeneity and outcomes for patients with JDM represents a major burden of disease and a challenge for clinical management. We sought to identify novel classes of patients having similar temporal patterns in disease activity and relate them to baseline clinical features. METHODS: Data were obtained for n = 519 patients, including baseline demographic and clinical features, baseline and follow-up records of physician's global assessment of disease (PGA), and skin disease activity (modified DAS). Growth mixture models (GMMs) were fitted to identify classes of patients with similar trajectories of these variables. Baseline predictors of class membership were identified using Lasso regression. RESULTS: GMM analysis of PGA identified two classes of patients. Patients in class 1 (89%) tended to improve, while patients in class 2 (11%) had more persistent disease. Lasso regression identified abnormal respiration, lipodystrophy and time since diagnosis as baseline predictors of class 2 membership, with estimated odds ratios, controlling for the other two variables, of 1.91 for presence of abnormal respiration, 1.92 for lipodystrophy and 1.32 for time since diagnosis. GMM analysis of modified DAS identified three classes of patients. Patients in classes 1 (16%) and 2 (12%) had higher levels of modified DAS at diagnosis that improved or remained high, respectively. Patients in class 3 (72%) began with lower DAS levels that improved more quickly. Higher proportions of patients in PGA class 2 were in DAS class 2 (19%, compared with 16 and 10%). CONCLUSION: GMM analysis identified novel JDM phenotypes based on longitudinal PGA and modified DAS.

[The analysis of clinical phenotypes and autoantibodies in juvenile dermatomyositis].

Objective: To elucidate the relationship between the myositis autoantibodies and clinical phenotypes of juvenile dermatomyositis (JDM). Methods: A total of 76 JDM patients admitted to the Children's Hospital of Chongqing Medical University from January 2017 to May 2020 were tested for myositis autoantibodies, including myositis-specific autoantibodies (MSAs) and myositis-associated autoantibodies (MAAs). Kruskal-Wallis test and logistic regression were used to analyze the relationship between the antibodies and clinical characteristics. Results: In the 76 cases, 37 were females and 39 males. Forty-three cases (53%) were MSAs positive, among which the most common subtypes were autoantibodies against nuclear matrix protein 2 (NXP2) (15/76, 20%), melanoma differentiation-associated protein 5 (MDA5) (13/76, 17%) and transcription intermediary factor 1 gamma (9/76, 11%). While 20 cases (26%) were positive for MAAs, among which anti-Ro-52 antibody (17/76, 22%) was the most common subtype. Sixteen patients (21%) had both MAAs and MSAs. The incidences of arthritis (9 cases), fever (8 cases), skin ulcers (5 cases) and macrophage activation syndrome (MAS) (1 case) were significantly higher in the patients with anti-MDA5 antibody among the antibody groups. Dysphasia (6 cases) and edema (8 cases) mainly occurred in patients with anti-NXP2 antibody. Children with anti-MDA5 antibody were more likely to develop arthritis (OR=10.636, 95%CI: 2.770-40.844, P=0.001), skin ulcers (OR=12.500, 95%CI: 2.498-62.522, P=0.002), fever (OR=5.600, 95%CI: 1.580-19.849, P=0.008) and interstitial lung disease (ILD) (OR=23.333, 95%CI: 4.750-114.616, P<0.01). In the patients with different subtypes of MSAs, the creatine kinase value was significantly lower in the anti-MDA5 group than those in the anti-aminoacyl-tRNA synthetase (P=0.03), anti-NXP2 (P<0.01), and MSAs-negative group (P=0.013). Conclusions: Most children with JDM have positive myositis autoantibodies, and will present with different clinical phenotypes based on different autoantibodies. And children with anti-MDA5 antibodies are likely to develop ILD and MAS. Therefore the detection of myositis-specific autoantibodies is important.

Where are we moving in the classification of idiopathic inflammatory myopathies?

PURPOSE OF REVIEW: Discoveries of myositis-specific antibodies, transcriptomic signatures, and clinicoseropathological correlation support classification of idiopathic inflammatory myopathies (IIM) into four major subgroups: dermatomyositis, immune-mediated necrotizing myopathy (IMNM), antisynthetase syndrome (ASS), and inclusion body myositis (IBM) whereas leaving polymyositis as a historical nonspecific diagnosis of exclusion. This review summarizes and comments on recent knowledge regarding the major subgroup of IIM. RECENT FINDINGS: Type 1 interferon (IFN1) pathway activation is the most prominent in dermatomyositis whereas type 2 interferon (IFN2) pathway activation is high in IBM and ASS; neither pathway is distinct in IMNM. Myxovirus-resistant protein A, IFN1 surrogate marker, is now one of definite dermatomyositis muscle biopsy criteria in the new 2018 European Neuromuscular Centre classification of dermatomyositis; the classification emphasizes on different categorization with and without dermatomyositis-specific antibody result. Novel HLA loci associated with anti-TIF1-γ, anti-Mi-2, and anti-Jo-1 antibodies in Caucasian population are identified. Associations of chaperon-assisted selective autophagy (CASA) and complement-mediated autoimmunity in IMNM as well as highly differentiated T cells in IBM are discovered. SUMMARY: Current IIM classification requires integrated clinicoseropathological approaches. Additional information, such as transcriptomics, HLA haplotyping, and potential biomarkers help tailoring categorization that may have future diagnostic and therapeutic implications.

[Idiopathic Inflammatory Myopathies]. / Idiopathische inflammatorische Myopathien.

Myositis is a rare and an extremely heterogeneous autoimmune disease, that causes muscle weakness. Currently, "idiopathic inflammatory myopathies (IIM)" is the preferred umbrella-term used to describe the disease complexity within individuals. IIM include dermatomyositis, polymyositis, inclusion body myositis, autoimmune necrotizing myopathy, overlap myositis and antisynthetase syndrome. Research activity concerning myositis was very intense over the past ten years and led to new diagnostic approach as well as to novel therapeutic strategies. Correct classification is the key for successful management. One single treatment regime for every possible organ involvement in all different forms of IIM is still not existing.

Different phenotypes in dermatomyositis associated with anti-MDA5 antibody: Study of 121 cases.

OBJECTIVES: The predominance of extramuscular manifestations (e.g., skin rash, arthralgia, interstitial lung disease [ILD]) as well as the low frequency of muscle signs in anti-melanoma differentiation-associated gene 5 antibody-positive (anti-MDA5+) dermatomyositis caused us to question the term myositis-specific antibody for the anti-MDA5 antibody, as well as the homogeneity of the disease. METHODS: To characterize the anti-MDA5+ phenotype, an unsupervised analysis was performed on anti-MDA5+ patients (n = 83/121) and compared to a group of patients with myositis without anti-MDA5 antibody (anti-MDA5-; n = 190/201) based on selected variables, collected retrospectively, without any missing data. RESULTS: Within anti-MDA5+ patients (n = 83), 3 subgroups were identified. One group (18.1%) corresponded to patients with a rapidly progressive ILD (93.3%; p < 0.0001 across all) and a very high mortality rate. The second subgroup (55.4%) corresponded to patients with pure dermato-rheumatologic symptoms (arthralgia; 82.6%; p < 0.01) and a good prognosis. The third corresponded to patients, mainly male (72.7%; p < 0.0001), with severe skin vasculopathy, frequent signs of myositis (proximal weakness: 68.2%; p < 0.0001), and an intermediate prognosis. Raynaud phenomenon, arthralgia/arthritis, and sex permit the cluster appurtenance (83.3% correct estimation). Nevertheless, an unsupervised analysis confirmed that anti-MDA5 antibody delineates an independent group of patients (e.g., dermatomyositis skin rash, skin ulcers, calcinosis, mechanic's hands, ILD, arthralgia/arthritis, and high mortality rate) distinct from anti-MDA5- patients with myositis. CONCLUSION: Anti-MDA5+ patients have a systemic syndrome distinct from other patients with myositis. Three subgroups with different prognosis exist.

Clasificación y manejo actual en dermatomiositis juvenil / Classification and current management in juvenile dermatomyositis

La Dermatomiositis Juvenil representa el 75-80% de las miopatías inflamatorias juveniles. Si bien, tiene baja incidencia y prevalencia, presenta importante morbilidad dada por sus manifestaciones cutáneas, musculares, pulmonares, gastrointestinales, cardiacas, entre otras. Corresponde a un desorden poligénico con múltiples factores gatillantes, que determina el desarrollo de una vasculopatía que lleva a atrofia muscular, inflamación y activación de vías del IFN-1. Actualmente su diagnóstico se basa en las guias EULAR/ACR (2017). En los últimos años, se han descubiertos distintos subtipos de la enfermedad, basados en el perfil de autoanticuerpos específicos de miositis, lo que ha permitido establecer pronóstico y estrategias terapéuticas personalizadas. El manejo farmacológico continúa basándose principalmente en el uso de corticoesteroides y DMARDs, así como también terapia biológica; en los últimos años, los inhibidores JAK han mostrado resultados promisorios, convirtiéndose en la más nueva alternativa terapéutica para el control de la enfermedad.

Juvenile Dermatomyositis represents 75-80% of juvenile inflammatory myopathies. Although it has a low incidence and prevalence, it presents significant morbidity due to its cutaneous, muscular, pulmonary, gastrointestinal and cardiac manifestations, among others. It corresponds to a polygenic disorder with multiple triggering factors, which determines the development of a vasculopathy that leads to muscle atrophy, inflammation and activation of IFN-1 pathways. Currently its diagnosis is based on the EULAR/ACR guidelines (2017). In recent years, different subtypes of the disease have been discovered, based on the profile of myositis-specific autoantibodies, which has made it possible to establish prognosis and personalized therapeutic strategies. Pharmacological management continues to be based mainly on the use of corticosteroids and DMARDs, as well as biological therapy; In recent years, JAK inhibitors have shown promising results, becoming the newest therapeutic alternative for disease control.

[Dermatomyositis: new antibody, new classification]. / Dermatomyosites Nouveaux anticorps, nouvelle classification.

Dermatomyositis are rare chronic auto-immune diseases characterized by cutaneous involvement. Diagnosis could be made in childhood or in aldult. There are some different clinical and histological presentation associated with different myositis specific antibody. There are five dermatomyositis specific autoantibodies, anti-Mi2, anti-Tif1-γ, anti-NXP2, anti-MDA5, and anti-SAE. Anti-Mi2 are associated with "classical form" of DM with cutaneous and muscular involvement. Anti-Tif1γ and anti-NXP2 are found in juvenile and adult dermatomyositis, and are associated with recurrent diseases with cutaneous involvement at the forefront. In adults, they are associated with cancer. Anti-MDA5 antibodies are associated with a systemic involvement and an interstitial lung disease. Finally, anti-SAE have been found only in adults, with a classic form.

TITLE: Dermatomyosites Nouveaux anticorps, nouvelle classification. ABSTRACT: Les dermatomyosites (DM) sont des maladies auto-immunes rares du groupe des myopathies inflammatoires idiopathiques, définies par une atteinte cutanée caractéristique. Elles peuvent survenir dans l'enfance, ou chez l'adulte. Il existe des variations phénotypiques entre les DM concernant la présentation cutanéomusculaire (ex: amyopathique) mais aussi la présentation extra-cutanéomusculaire (ex: atteinte pulmonaire ou articulaire associée). Le caractère auto-immun de ces pathologies est souligné dans 60 % des cas par la présence d'anticorps spécifique de myosite. Ces derniers sont associés à la présence de caractéristiques cliniques, histologiques, mais aussi pronostiques. Ils sont au nombre de cinq, les anti-Mi2, anti-Tif1-γ, anti-NXP2, anti-MDA5 et anti-SAE. Les anti-Mi2 sont associées à une forme clinique cutanée classique, une atteinte musculaire souvent sévère au diagnostic et une bonne évolution sous traitement. Les deux suivants, fréquents chez l'enfant et l'adulte, sont associés à des formes récidivantes cutanées et sont fortement associés aux cancers chez l'adulte. Les anti-MDA5 sont les anticorps associés aux formes les plus systémiques avec une atteinte pulmonaire interstitielle rapidement progressive pouvant être très grave. Enfin, les anti-SAE n'ont été décrits que chez l'adulte, avec une atteinte classique.

Classification of idiopathic inflammatory myopathies: pathology perspectives.

PURPOSE OF REVIEW: Idiopathic inflammatory myopathies (IIM) are rare diseases with heterogenous clinicopathological features. In recent years, new classification systems considering various combinations of clinical, serological, and pathological information have been proposed. This review summarizes recent clinicoseropathological development in major subgroups of IIM. RECENT FINDINGS: Considering clinicoseropathological features, IIM are suggestively classified into four major subgroups: dermatomyositis, immune-mediated necrotizing myopathy (IMNM), antisynthetase syndrome (ASS), and inclusion body myositis (IBM). Many historically diagnosed polymyositis have been mainly reclassified as IBM, IMNM, and ASS. Different types of myositis-specific antibodies (MSA) suggest distinct clinicopathological subsets of IIM. Excluding IBM, at least one-third of the IIMs have no known associated MSA. SUMMARY: MSA are crucial for IIM classification but can be negative. Thus, IIM should be universally classified using stepwise or integrated information on clinical, serological, and pathological findings.

Identification of 6 dermatomyositis subgroups using principal component analysis-based cluster analysis.

OBJECTIVE: Dermatomyositis (DM) is a heterogeneous disease with a wide range of clinical manifestations. The aim of the present study was to identify the clinical subtypes of DM by applying cluster analysis. METHODS: We retrospectively reviewed the medical records of 720 DM patients and selected 21 variables for analysis, including clinical characteristics, laboratory findings, and comorbidities. Principal component analysis (PCA) was first conducted to transform the 21 variables into independent principal components. Patient classification was then performed using cluster analysis based on the PCA-transformed data. The relationships among the clinical variables were also assessed. RESULTS: We transformed the 21 clinical variables into nine independent principal components by PCA and identified six distinct subgroups. Cluster A was composed of two sub-clusters of patients with classical DM and classical DM with minimal organ involvement. Cluster B patients were older and had malignancies. Cluster C was characterized by interstitial lung disease (ILD), skin ulcers, and minimal muscle involvement. Cluster D included patients with prominent lung, muscle, and skin involvement. Cluster E contained DM patients with other connective tissue diseases. Cluster F included all patients with myocarditis and prominent myositis and ILD. We found significant differences in treatment across the six clusters, with clusters E, C and D being more likely to receive aggressive immunosuppressive therapy. CONCLUSION: We applied cluster analysis to a large group of DM patients and identified 6 clinical subgroups, underscoring the need for better phenotypic characterization to help develop individualized treatments and improve prognosis.

[Dermatomyositis].

When examining the skin manifestations of dermatomyositis, it is important to systematically observe the frequently affected sites. The head and the hands are particularly important. It is critical to look not just for symptoms included in the classification criteria, such as heliotrope rash and Gottron's papules/signs, but also for other rashes. Recent studies have demonstrated that specific autoantibodies are useful tools to subgroup dermatomyositis, and the skin manifestations are also closely correlated with these autoantibodies.

Overlap myositis, a distinct entity beyond primary inflammatory myositis: A retrospective analysis of a large cohort from the REMICAM registry.

BACKGROUND: Inflammatory idiopathic myositis (IIM) comprises a heterogeneous group of systemic muscular diseases that can occur together with other connective tissue diseases (CTD), named overlap myositis (OM). The question of whether OM is a distinct entity still remains controversial. AIM: The present study was conducted to assess the clinical and prognostic differences between patients diagnosed with OM, primary polymyositis (PM) and primary dermatomyositis (DM). METHOD: The study consists of a retrospective longitudinal and multicenter series of IIM patients. Patients were classified as OM, PM and DM. Overlap myositis was defined as patients fulfilling criteria for IIM plus criteria for other CTD (namely systemic sclerosis, systemic lupus erythematosus, mixed connective tissue disease, rheumatoid arthritis and primary Sjögren's syndrome). RESULT: A total of 342 patients were included (98 OM, 137 PM and 107 DM). Overlap myositis patients, in comparison with PM and DM, showed significant differences, with more extramuscular involvement, particularly more arthritis (66%, 34.6% and 48.1%, respectively), puffy fingers (49.5%, 11.1% and 24.3%), sclerodactyly (45.4%, 2.2% and 2%), dysphagia (41.8%, 18.2% and 26.4%), Raynaud phenomenon (65.3%, 16.9% and 19.8%), leucopenia (28.9%, 2.2% and 8.4%), thrombocytopenia (8.2%, 2.2% and 1.9%), interstitial lung disease (ILD) (48%, 35% and 30.8%), renal manifestations (13.4%, 3.7% and 1.9%), and more severe infections (41.3%, 26.7% and 21%). No significant differences were found in survival between groups in log rank test (P = 0.106). Multivariate adjusted survival analyses revealed a worse prognosis for severe infections, ILD and baseline elevation of acute phase reactants. CONCLUSION: Overlap myositis stands out as a distinct entity as compared to PM and DM, featuring more extramuscular involvement and more severe infections. Close monitoring is recommended in this subset for early detection and treatment of possible complications.

Connective Tissue Disease: Current Concepts.

Connective tissue diseases often prominently affect the skin, requiring dermatologists to play an important role in diagnosis and treatment of these patients. Herein we describe updates on the pathogenesis, clinical features, and treatment of 4 major connective tissue diseases: dermatomyositis, cutaneous lupus erythematosus, limited scleroderma (morphea), and cutaneous vasculitis. Many of these updates promise to improve clinical care of patients who suffer from dermatologic involvement of these diseases and are the result of research performed by dermatologists who have expertise in these conditions.

The diagnosis and classification of amyopathic dermatomyositis: a historical review and assessment of existing criteria.

BACKGROUND: Diagnostic criteria are used to identify a patient having a disease in a clinical setting, whereas classification criteria create a well-defined population for research purposes. The diagnosis and classification of amyopathic dermatomyositis (ADM) have not been recognized by most existing criteria for idiopathic inflammatory myopathies (IIMs). To address this, several criteria were proposed to define ADM either as a distinct disease entity or as a subset of the spectrum of IIMs. OBJECTIVES: To discuss the diagnosis and classification of ADM and to assesses the available criteria in identifying cases of ADM and/or distinguishing it from dermatological mimickers such as lupus erythematosus. METHODS: We conducted an extensive literature search using the PubMed database from June 2016 to August 2018, using the search terms 'amyopathic dermatomyositis', 'diagnosis' and 'classification'. RESULTS: The European League Against Rheumatism (EULAR)/American College of Rheumatology (ACR) criteria, which are the only validated classification criteria for adult and juvenile IIM and their major subgroups, include three cutaneous items (Göttron sign, Göttron papules, heliotrope rash) to be able to classify ADM. This international and multispecialty effort is a huge step forward in the classification of skin-predominant disease in dermatomyositis. However, about 25% of the population with ADM do not meet two out of the three skin features and are misdiagnosed or classified as having a different disease entity, most commonly lupus erythematosus. CONCLUSIONS: These gaps rationalize the continuous assessment and improvement of existing criteria and/or the development of validated, separate and skin-focused criteria for DM.