Myositis-specific Antibodies Research Articles

High Prevalence of Myositis-Specific and Associated Antibodies in Patients with Pulmonary Hypertension.

Pulmonary hypertension (PH) is a serious condition linked to immune-system dysfunction. Myositis-specific/associated antibodies (MSAs/MAAs) play a role in idiopathic inflammatory myopathy (IIM) and interstitial lung disease (ILD), but their significance in PH remains unclear. We believe the presence of these antibodies may be underestimated. This study analyzed adult PH patients without pre-existing IIM for MSA/MAA prevalence using a line-blot assay. We compared PH patients with and without ILD signs to a cohort clinically suspected of IIM/ILD (n = 558). Our PH cohort (n = 121) showed a significantly higher prevalence of overall weak positive MSAs/MAAs and positive overlap syndrome-associated MAAs than the suspected IIM/ILD group (p < 0.001). Notably, MSAs/MAAs were found in PH patients both with and without ILD, though more prevalent in those with ILD. Anti-synthetase and anti-overlap syndrome antibodies were the most common. Our study is the first to systematically show a high MSA/MAA prevalence in PH without IIM presentation. This highlights the need to consider PH when diagnosing MSA/MAA-associated conditions. We recommend MSA/MAA screening for newly diagnosed PH, especially in those with ILD, for early detection and potential immunomodulatory treatment. Further research should explore the link between MSAs/MAAs and PH, and the value of monitoring patients with weak MSA/MAA positivity over time.

Diabetic myonecrosis complicated by emphysematous pyomyositis and abscess caused by Escherichia coli: a case report

BackgroundNecrotizing myopathies and muscle necrosis can be caused by immune-mediated mechanisms, drugs, ischemia, and infections, and differential diagnosis may be challenging.Case presentationWe describe a case of diabetic myonecrosis complicated by pyomyositis and abscess caused by Escherichia coli. A white woman in her late forties was admitted to the hospital with a 1.5 week history of bilateral swelling, weakness, and mild pain of the lower extremities and inability to walk. She had a history of type 1 diabetes complicated by diabetic retinopathy, neuropathy, nephropathy, and end-stage renal disease. C-reactive protein was 203 mg/l, while creatinine kinase was only mildly elevated to 700 IU/l. Magnetic resonance imaging of her lower limb muscles showed extensive edema, and muscle biopsy was suggestive of necrotizing myopathy with mild inflammation. No myositis-associated or myositis-specific antibodies were detected. Initially, she was suspected to have seronegative immune-mediated necrotizing myopathy, but later her condition was considered to be explained better by diabetic myonecrosis with multifocal involvement. Her symptoms alleviated without any immunosuppressive treatment. After a month, she developed new-onset and more severe symptoms in her right posterior thigh. She was diagnosed with emphysematous urinary tract infection and emphysematous myositis and abscess of the right hamstring muscle. Bacterial cultures of drained pus from abscess and urine were positive for Escherichia coli. In addition to abscess drainage, she received two 3–4-week courses of intravenous antibiotics. In the discussion, we compare the symptoms and findings typically found in pyomyositis, immune-mediated necrotizing myopathy, and diabetic myonecrosis (spontaneous ischemic necrosis of skeletal muscle among people with diabetes). All of these diseases may cause muscle weakness and pain, muscle edema in imaging, and muscle necrosis. However, many differences exist in their clinical presentation, imaging, histology, and extramuscular symptoms, which can be useful in determining diagnosis. As pyomyositis often occurs in muscles with pre-existing pathologies, the ischemic muscle has likely served as a favorable breeding ground for the E. coli in our case.ConclusionsIdentifying the etiology of necrotizing myopathy is a diagnostic challenge and often requires a multidisciplinary assessment of internists, pathologists, and radiologists. Moreover, the presence of two rare conditions concomitantly is possible in cases with atypical features.

Clinical features and prognosis of idiopathic inflammatory myopathies with coexistent multiple myositis-specific antibodies.

This study aimed to evaluate the clinical significance of the coexistence of 2 or more myositis-specific antibodies (multiple MSAs) in adult patients with idiopathic inflammatory myopathies (IIM). We assessed a cohort of 202 consecutive patients with IIM. Clinical features and survival rates were compared between patients with and without multiple MSAs. Of those 202 patients, 44 (21.8%) were found to have multiple MSAs. 63.6% of the 44 patients tested positive for anti-aminoacyl-tRNA synthetase antibodies (anti-ARS+) and 52.3% positive for anti-melanoma differentiation-associated protein-5 antibody (anti-MDA5+). The presence of multiple MSAs was associated with less rapidly progressive interstitial lung disease (RP-ILD), fever, rash, periungual erythema, more muscle involvement and dysphagia, higher albumin level, and higher positive rate of ANA antibody in anti-MDA5+ population. In anti-ARS+ population with multiple MSAs, there were more V-neck sign, skin ulcers, dysphagia and peripheral edema. No differences in survival rates were observed between patients with or without multiple MSAs in the overall and anti-ARS+ populations. However, the survival rate in anti-MDA5+ population with multiple MSAs was significantly higher than those without multiple MSAs (p = 0.003). Moreover, multiple MSAs remained an independent protective factor against mortality in multivariable Cox regression analysis of anti-MDA5+ population [HR 0.108 (95% CI 0.013, 0.908), p=0.041]. Multiple MSAs coexist in some IIM patients and their existence indicates mixed features from concomitant MSAs in anti-MDA5+ population and anti-ARS+ population. Identifying multiple MSAs could help to discover a more favourable disease phenotype with decreased mortality in anti-MDA5+ population.

Anti-synthase syndrome associated with SARS-Cov-2 infection

BackgroundAnti-synthetase syndrome (AS) is a rare autoimmune idiopathic inflammatory myopathy (IIM) with diverse manifestations, including arthritis, interstitial lung disease (ILD), Raynaud’s phenomenon, unexplained persistent fever, and mechanic’s hands.Case presentationWe present the case of a 72-year-old woman, previously healthy, who was admitted to our hospital for treatment of cough and rapid breathing. The patient had elevated white blood cells and C-reactive protein, and tested negative for severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2). She was initially diagnosed with community-acquired pneumonia and received tamoxifen for anti-infection treatment, but her dystonia worsened. She eventually required non-invasive ventilator support, tested positive for SARS-Cov-2 again, and started antiviral therapy, corticosteroids to reduce alveolar effusion, anticoagulation, and other treatments. However, her condition continued to deteriorate, with the lowest oxygenation index reaching only 80mmHg. Ultimately, she underwent tracheal intubation and mechanical ventilation. Chest CT revealed rapid progressive interstitial changes in her lungs, and her hands showed noticeable fraternization changes. At this point, we suspected that the novel coronavirus infection might be associated with autoimmune diseases. The patient’s autoimmune antibody spectrum showed positive results for anti-recombinant RO-52 antibody and myositis-specific antibody anti-alanyl tRNA synthetase (anti-PL-12). The patient was treated with dexamethasone sodium phosphate for anti-inflammatory and anti-fibrotic effects. After successful extubation, the patient was discharged with only oral prednisone tablets at a dose of 30 mg.ConclusionsThis case presents an early diagnosis and successful treatment of anti-synthetase syndrome combined with SARS-Cov-2 infection, emphasizing the importance of comprehensive physical examination. Additionally, it highlights the rapid progression of interstitial lung disease under SARS-Cov-2 infection, which is often difficult to distinguish on imaging. In cases where treatment for SARS-Cov-2 infection is ineffective, early screening for autoimmune diseases is recommended. As there is currently no standardized method for treating AS-ILD, the successful treatment of this case provides a reference for clinical research on anti-synthetase syndrome in the later stage.

Myositis-associated antibodies predict the severity of lung involvement in adult patients with inflammatory myositis - a cohort study of 70 adult patients with myositis in a single center.

Idiopathic inflammatory myopathies (IIMs) encompass a diverse group of diseases characterized by considerable variability in clinical manifestations, antibody profiles, and responsiveness to immunosuppressive therapies. This study aimed to investigate the association between organ involvement and distinct myositis autoantibodies in individuals with IIM in a single-center cohort. Patients with ICD diagnoses M33.1, M33.2, M33.9, or M609 who (1) had been tested with Euroline blot assay for myositis autoantibodies and (2) met the classification criteria of definite/probable polymyositis (PM) or dermatomyositis (DM), anti-synthetase syndrome (ASS), or inclusion body myositis (IBM) were included. Medical journals were retrospectively examined with respect to clinical disease features. Seventy patients (median age 58 years; 66% females) were included and represented the following diagnosis: PM (n = 23), DM (n = 21), ASS (n = 23), and IBM (n = 3). Most of the patients (87%) presented a muscle biopsy indicative of myositis. The presence of autoantibodies was as follows: myositis-specific antibodies, MSA (n = 53), myositis-associated antibodies, MAA (n = 33), both MSA + MAA (n = 24), MSA only (n = 29), MAA only (n = 9), no MSA, or MAA (n = 8). Anti-Jo-1 was the most common MSA (19%), whereas the most common MAA was anti-Ro/SSA52 (31%). We observed a significant association between antibody patterns and lung disease. In our cohort, 47% of the patients in the whole study group, 86% of patients with anti-SSA52, and 100% with anti-Jo-1 had pulmonary involvement. Patients with both MSA and MAA had a higher incidence of lung disease and decreased CO-diffusion capacity. This was especially prominent in anti-Ro/SSA52-positive patients. Interestingly, none of the patients suffered from lung disease if only antibodies against Mi-2α, Mi-2β, NXP2, HMGCR, and TIF1γ were present or no MSA/MAA were detected. The simultaneous presence of both MAA and MSA indicates an increased risk of lung involvement in patients with inflammatory myopathies. The presence of any MAA, and especially anti-Ro/SSA52, is associated with more severe pulmonary disease. Our data suggest that MAA antibodies might be relevant markers for early detection and treatment of lung involvement in IIM.

Anti-aminoacyl tRNA synthetase antibodies showing the discrepancy between enzyme-linked immunosorbent assay and RNA-immunoprecipitation

Anti-aminoacyl-tRNA synthetase (ARS) antibodies are myositis-specific antibodies associated with anti-synthetase syndrome (ASSD). Some patients are positive for anti-ARS antibodies on enzyme-linked immunosorbent assay (ELISA) but negative on RNA-immunoprecipitation (RNA-IP) (the gold standard method). Whether these patients should be considered truly positive for anti-ARS antibodies remains unclear. Therefore, we investigated the clinical characteristics of these patients and verified the authenticity of their anti-ARS positivity. Patients who were positive for anti-ARS antibodies on ELISA were divided into the non-discrepant (positive on RNA-IP, n = 52) and discrepant (negative on RNA-IP, n = 8) groups. Patient clinical characteristics were compared between the groups. For each positive individual, the authenticity of anti-ARS antibody positivity on ELISA was cross-examined using protein-IP and western blotting. All patients in the discrepant group had lung involvement, including five (63%) with interstitial lung disease. The overall survival time was significantly lower in the discrepant group than in the non-discrepant group (p < 0.05). Validation tests confirmed the presence of anti-ARS antibodies in the sera of the discrepant group but indicated different reactivity from typical anti-ARS antibodies. In conclusion, some anti-ARS antibodies are detected by ELISA but not RNA-IP. Such anti-ARS antibody discrepancies need further elucidation to attain validation of the diagnostic process in ASSD.

Polymyositis is a rare and favourable outcome subtype of idiopathic inflammatory myopathy in Chinese patients.

To investigate the prevalence and characteristics of typical polymyositis (PM) in Chinese patients with idiopathic inflammatory myopathy (IIM). Patients diagnosed with IIM according to the 2017 EULAR/ACR criteria were included. Serological aspects including myositis-specific antibodies (MSA) and pathological data were re-evaluated. The diagnosis of typical PM was strictly done using the pathological criteria, while excluding other IIM subtypes such as dermatomyositis (DM), immune-mediated necrotising myopathies (IMNM), anti-synthetase syndrome (ASS), and sporadic inclusion body myositis (sIBM), based on their respective diagnostic criteria. A total of 544 IIM patients with muscle biopsy were involved, and 129 of them were diagnosed with initial PM according to the 2017 EULAR/ACR criteria. Only 6 (1.1%, 6/544) patients met the strict definition of typical PM after re-evaluation. Patients with typical PM were MSA-negative (100% vs. 35.7%, p=0.003) and had CD8+ T cells surrounding or invading non-necrotic muscle fibres in muscle biopsies (100% vs. 7.8%, p<0.001) compared to the initially diagnosed PM patients. All typical PM patients achieved clinical remission at the second-year follow-up. Typical PM patients had a favourable prognosis compared to MSA-negative IMNM and unspecific myositis patients. Strictly defined typical PM is a rare clinical subtype in Chinese IIM patients. Typical PM patients with classical pathology were MSA-negative and responded well to treatment and had a favourable prognosis. It is crucial for clinicians to combine clinical, serological, and pathological features to properly distinguish PM from other IIM subtypes.

Cancer-associated myositis before and after the COVID-19 pandemic onset: a changing trend.

During the COVID-19 pandemic, there was a significant impact on the management of non-COVID-19 related diseases, potentially increasing the incidence of paraneoplastic syndromes such as cancer-associated myositis (CAM).The aim of this study is to determine the incidence of CAM in our cohort before and after the COVID-19 pandemic onset. We included patients with idiopathic inflammatory myopathy (IIM), diagnosed between June 2016 and June 2023. The patients were divided into two groups according to the date of IIM diagnosis. We included 132 patients; 65.1% (n=86) were diagnosed prior to and 34.9% (n=46) after the COVID-19 pandemic. The most common IIM was dermatomyositis (DM) before and after the COVID-19 pandemic onset (p=0.750). The most frequent myositis-specific antibody (MSA) before the COVID-19 pandemic was anti-Mi2 (15.1%). After the COVID-19 pandemic onset, anti-TIF1γ was the most common MSA (21.7%), with a significantly higher relative prevalence (p=0.006). The incidence of CAM was significantly higher after the COVID-19 pandemic onset (11 vs. 3 new cases, p<0.002). Patients with CAM more frequently had anti-TIF1γ-positivity (p<0.001) and a diagnosis after the pandemic (p=0.001) than non-CAM-IIM patients. No significant differences were found regarding vaccination status or previous COVID-19 infection in CAM and non-CAM-IIM patients. Diagnosis after the COVID-19 pandemic was an independent predictor of CAM among IIM patients (OR 0.012, 95% CI 0.000-0.400, p=0.013), regardless of age, sex or previous COVID-19 infection. There was a significant increase in the incidence of CAM after the COVID-19 pandemic. IIM diagnosis after the COVID-19 pandemic was an independent predictor of CAM.

Anti-SAE dermatomyositis: clinical and histologic characteristics from a monocentric Italian cohort.

Multiple myositis-specific antibodies have been identified, each associated with different clinical subsets of dermatomyositis (DM). Anti-SAE associated DM is considered the least studied subset. Our study aimed to evaluate the clinical and histological characteristics of DM patients with anti-SAE antibodies. As reference, patients with anti-Mi2 antibodies associated DM, representing a well-characterised subset, were analysed. We recorded data from our DM cohort in the INflammatory MYositis REgistry (INMYRE). Patients were divided into two groups: those positive for anti-SAE and those positive for anti-Mi2 antibodies. Clinical characteristics, including skin, muscle, and extra-muscular involvements, were recorded. Available muscle biopsies were compared between the two groups. Of 92 DM patients, 10 (10.9%) were positive for anti-SAE and 17 (18.5%) for anti-Mi2. Anti-SAE positive DM patients showed classic DM findings but were characterised by a higher prevalence of skin itching (60% vs. 11.8%, p<0.01), shawl sign (40% vs. 5.9%, p<0.05) and lung involvement (30% vs. 0%, p<0.05) compared to anti-Mi2 positive patients. Furthermore, anti-SAE positive DM patients showed lower creatine kinase levels than those with anti-Mi2 (median [IQR]: 101 [58-647] vs. 1984 [974-3717], p<0.05) and a lower percentage of muscle fibre degeneration and necrosis (1.5%±1.7 vs. 5.9%±3.2, p<0.05) in muscle biopsies. No other differences were observed. Anti-SAE DM represents a disease subset characterised by classic cutaneous involvement often associated with itching, less severe muscle involvement, but potential pulmonary involvement that should always be investigated in these patients.

Anti-synthetase syndrome is associated with a higher risk of hospitalization among patients with idiopathic inflammatory myopathy and COVID-19.

Data with fine granularity about COVID-19-related outcomes and risk factors were still limited in the idiopathic inflammatory myopathies (IIMs) population. This study aimed to investigate clinical factors associated with hospitalized and severe COVID-19 in patients with IIMs, particularly those gauged by myositis-specific antibodies. This retrospective cohort study was conducted in the Renji IIM cohort in Shanghai, China, under an upsurge of SARS-CoV-2 omicron variant infections from December 2022 to January 2023. Clinical data were collected and analyzed by multivariable logistic regression to determine risk factors. High-dimensional flow cytometry analysis was performed to outline the immunological features. Among 463 infected patients in the eligible cohort (n=613), 65 (14.0%) were hospitalized, 19 (4.1%) suffered severe COVID-19, and 10 (2.2%) died. Older age (OR=1.59/decade, 95% CI 1.18 to 2.16, p=0.003), requiring family oxygen supplement (2.62, 1.11 to 6.19, 0.028), patients with anti-synthetase syndrome (ASyS) (2.88, 1.12 to 7.34, 0.027, vs. other dermatomyositis), higher IIM disease activity, and prednisone intake >10mg/day (5.59, 2.70 to 11.57, <0.001) were associated with a higher risk of hospitalization. Conversely, 3-dose inactivated vaccination reduced the risk of hospitalization (0.10, 0.02 to 0.40, 0.001, vs. incomplete vaccination). Janus kinase inhibitor (JAKi) pre-exposure significantly reduced the risk of severe COVID-19 in hospitalized patients (0.16, 0.04 to 0.74, 0.019, vs. csDMARDs). ASyS patients with severe COVID-19 had significantly reduced peripheral CD4+ T cells, lower CD4/CD8 ratio, and fewer naive B cells but more class-switched memory B cells compared with controls. ASyS and family oxygen supplement were first identified as risk factors for COVID-19-related hospitalization in patients with IIMs. JAKi pre-exposure might protect IIM patients against severe COVID-19 complications.

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.

Magnetic resonance imaging patterns revealing muscle pathology and clinical features in idiopathic inflammatory myopathies.

Idiopathic inflammatory myopathies (IIMs) are autoimmune disorders significantly impacting skeletal muscles; however, the precise correlation between muscle magnetic resonance imaging (MRI) findings, muscle pathology, disease subtypes and clinical characteristics remains uncertain. Thus, we investigated the association of muscle MRI findings in IIMs with muscle pathology and clinical features. New-onset IIM patients underwent proximal upper and/or lower limb muscle MRI. Patterns of muscle oedema on MRI were categorised into fascial, honeycomb, peripheral, foggy, dense, or coarse dot patterns and compared with inflammatory cell infiltration sites in corresponding muscle biopsies. The incidence of MRI patterns was examined in patient subgroups using myositis-specific antibodies (MSAs) and 2017 EULAR/ACR classification criteria. Univariate and multivariate analyses were conducted to determine the odds ratios (ORs) of MRI findings for clinical characteristics. Fifty-six of 85 patients underwent muscle biopsy. Foggy, honeycomb and fascial patterns at biopsy sites correlated with inflammatory cell infiltration in the endomysium (OR 11.9, P = 0.005), perimysium (OR 6.0, P = 0.014) and fascia (OR 16.9, P < 0.001), respectively. Honeycomb and foggy patterns were characteristic of patients with anti-TIF1γ or anti-Mi2 antibodies and MSA-negative dermatomyositis, and those with anti-SRP or anti-HMGCR antibodies and MSA-negative polymyositis (PM), respectively. The honeycomb pattern positively correlated with malignancy (OR 6.87, P < 0.001) and Gottron sign (OR 8.05, P = 0.002); the foggy pattern correlated with muscle weakness (OR 11.24, P = 0.005). The dense dot pattern was associated with dysphagia (OR 6.27, P = 0.006) and malignancy (OR 8.49, P = 0.002). Muscle MRI holds promise in predicting muscle pathology, disease subtypes and clinical manifestations of IIMs.

Clinical and immunological characteristics and prognosis of patients with autoantibody negative dermatomyositis: a case control study.

Myositis-specific antibodies (MSAs) and myositis-associated antibodies (MAAs) are associated with distinctive dermatomyositis (DM)clinical phenotypes. The aim of this study is to explicate the clinical andimmunologicalfeatures of MSAs-negative DM patients. A total of 515 individuals diagnosed with DM was screenedfrom 2013 to 2022 and 220 DM patients were enrolled in this retrospective cohort. Clinical and laboratory data of these patients were analyzed. MSAs-negative DMpatients were categorized into two groups: MAAs-negative(MSAs (-)/MAAs (-)) groupand MAAs-positive (MSAs (-)/MAAs (+))group. The percentage of Raynaud's phenomenon (P=0.026) was higher in the MSAs (-)/MAAs (+) DM patients than the MSAs-positiveDM patients and MSAs (-)/MAAs (-) DMpatients. The proportion of rapidly progressive interstitial lung disease (RP-ILD) in the MSAs-negative DM patients was lower than that in the MSAs-positive group. The MSAs (-)/MAAs (+) group had a higher proportion of organizing pneumoniaand usual interstitial pneumonia (P=0.011), and elevated eosinophils in their bronchoalveolar lavage fluid (P=0.008). Counts of lymphocytes (P=0.001) and CD16+CD56+ natural killer (NK) cells (P=0.012) were higher in the MSAs-negative group. Additionally, the percentage of CD4+TNFα+ (P=0.040), CD4+IFNγ+ (P=0.037), and CD4+IL-2+ (P=0.018) cells among totalCD4+ T cells were higher in the MSA-negative DM patients compared with the MSAs-positive DM patients. Besides, MSAs-negative patients demonstrated a more favorable prognosis than MSAs-positive patients. Multivariable regression analysis identified advanced onsetage, higher level ofcarcinoembryonic antigen (CEA), and RP-ILD as risk factors for mortality in DM patients. Compared with MSAs-positive group,MSAs-negative DM patients suffered less from organ involvement compared with MSAs-positive group and tend to have better prognosis. Key Points MSAs-negative DM patients exhibited distinct characteristics in comparison with MSAs-positive DMpatients: • The MSAs (-)/MAAs (+) DM patientsdemonstrated a higher prevalence of organizing pneumonia (OP)and usual interstitial pneumonia (UIP), and elevated eosinophil counts in bronchoalveolar lavage fluid. • CEA levels were lower in MSAs-negative patients compared with MSAs-positive patients. • Elevated counts of lymphocytes and CD16+CD56+ NK cells were identified in the MSAs-negativepatients. Additionally, proportions of CD4+TNFα+, CD4+IFNγ+, and CD4+IL-2+ cells among total CD4+ T cells were higher in the MSAs-negative DM patients compared with DM MSAs-positive DM patients. • MSAs-negative DMpatients had a more favorable prognosis than MSAs-positive DMpatients. A multivariable regression analysis revealed the advanced onsetage, highCEA levels, and RP-ILD were risk factors for mortality in DM patients.

Prevalence of cutaneous manifestations and myositis-specific antibodies in COVID-19 patients and Anti-PL7 antibodies association with pulmonary radiological severity: A retrospective study.

Dermatomyositis (DM) is an idiopathic immune-mediated myopathy, and may involve many organs, including muscles, skin and lungs. Myositis-specific autoantibodies (MSAs) are a useful aid in diagnosis DM and identifying its clinical subtype. During the COVID-19 pandemic, several studies found clinical similarities regarding lung involvement in both COVID-19 and DM. Such similarities have prompted speculation of a common pathogenetic mechanism. Indeed, viral infections are well-known triggers of autoimmune diseases. This prompted us to investigate whether circulating MSAs could be markers of the severity of lung involvement and of clinical outcome in COVID-19 patients. Moreover, we investigated the presence of cutaneous signs of DM in COVID-19 patients. We conducted a retrospective cohort study on 178 hospitalized patients affected by COVID-19. The diagnosis was confirmed by naso-pharyngeal swab positivity for SARS-CoV-2. The severity of lung involvement was assessed by assigning to each patient a radiological score ranging from 1 to 4, based on chest imaging (chest X-rays or CT scans). Serum samples were tested for MSAs. Anti-PL-7 antibodies were detected in 10.1% of patients and were found to be associated with an increased risk of severe pulmonary involvement (p = 0.019) and a worse prognosis in COVID-19 patients. Cutaneous lesions were observed in 26.4% of patients. However, none were cutaneous manifestations of DM. The detection of anti-PL7 antibodies might predict severe pulmonary involvement and a worse prognosis in COVID-19 patients.

Utility of positron emission tomography as a new tool for muscle involvement in patients with idiopathic inflammatory myositis: a controlled study.

Idiopathic inflammatory myositis (IIM) represents a rare group of disease that can affect multiple organs in addition to the muscles. 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) is an emerging scanning method that is widely used in diagnosing, staging and response to treatment in patients with cancer. In this study, we aimed to evaluate the muscle involvement in PET/CT which was performed for malignancy screening and its correlation with myositis-specific antibodies (MSA) and/or myositis-associated antibodies (MAA) in patients with IIM. IIM patients who fulfilled 2017 EULAR/ACR classification criteria and had PET-CT scans during the active phase of myositis (within two weeks of starting steroids) were included into the study. Age and sex matched participants with history of malignancy (non-IIM patients) were defined as control group. Data of 160 IIM patients were evaluated and 34 patients (of 64.7% female) whose PET/CT results were available, included into the study. Fourteen patients with diagnosis of malignancy without IIM (non-IIM patients) defined as the control group. Sensitivity and specificity of a positive FDG muscle uptake were 37.1% and 100%, 65.7% and 92.9%, 91.4% and 7.1% compared to liver, mediastinum and LTM uptakes, respectively. In multivariate analysis, higher baseline CRP (p=0.017, confidence interval [CI] 95%: 1.03-1.36, OR:1.18) and LDH (p=0.029, CI 95%:1.001-1.017, OR:1.01) levels were associated with muscle PET/CT positivity. In patients with active IIM, median muscle FDG uptake with PET/CT was higher compared to non-IIM. PET/CT may be used for the evaluation of extent and activity in patients with IIM.

Current update on dermatomyositis

Dermatomyositis (DM) is arare autoimmune disease with involvement of skin and muscle that is classified as an idiopathic inflammatory myopathy. In addition to cutaneous lesions as well as weakness and atrophy of muscles, the heart and lungs are the major affected organs. DM occurs in association with malignant tumors in 20% of affected adults. The pathogenesis of the disease is not completely understood. DM is amultifactorial disease influenced by genetic, environmental and immunological factors. The immune response is characterized by activation of innate and adaptive immune mechanisms and astrong activation of the typeI interferon pathway. Myositis-specific antibodies are characteristic of DM and allow differential diagnosis. Therapies include corticosteroids, antimalarials, immunoglobulins, biologics such as rituximab or JAK inhibitors. Early diagnosis and treatment are essential for the prognosis.

O08 Severely pruritic juvenile dermatomyositis

Abstract A 7-year-old female with type IV skin and autism spectrum disorder presented with a 4 month history of progressive proximal myopathy, weight loss and 20 month history of a worsening, intensely pruritic rash. Cutaneous examination showed a widespread eczematous eruption, post-inflammatory hypopigmentation, heliotrope rash and firm subcutaneous changes, in addition to palmar-plantar papules, pustules and burrows. Extra-cutaneous findings included multiple fixed flexion deformities and muscle wasting. Investigations revealed a normocytic anaemia, elevated muscle enzymes, strongly positive anti-nuclear antibodies and negative myositis-specific antibodies. Whole body MRI reported proximal muscle oedema. Skin biopsy demonstrated lichenoid and perifollicular inflammation, dermal mucin and subcutaneous calcification. Clinical findings were consistent with a diagnosis of juvenile dermatomyositis (JDM), complicated by concurrent scabies. Prednisolone in combination with methotrexate was commenced as first-line therapy in line with current consensus JDM treatment plans, in addition to topical steroids and sun protection. Muscle power started to improve after 5 months but ongoing cutaneous inflammation prompted second-line therapy with IV immunoglobulin. Oral ivermectin was required for the management of scabies due to topical permethrin failure. JDM is a rare autoimmune small-vessel vasculopathy with significant morbidity and limited evidence-based guidelines. Unlike adult-onset disease there is no racial predilection or association with malignancy. Calcinosis is more common in children but early treatment reduces disease complications. JDM has a variable disease course with a median time to remission of 4.67 years. Residual skin changes are increasingly recognised to be an early predictor of prolonged recovery time and these patients may benefit from biologic agents.

Contrasting Risk Profile in Idiopathic Inflammatory Myopathy (IIM) Patients with Cancer Before and After IIM Diagnosis

Background: Patients with adult-onset idiopathic inflammatory myopathy (IIM) were at risk of cancer. While the recently published international guideline on cancer screening suggested cancer risk stratification in patients with newly diagnosed IIM, the difference in clinical and serological risk profile among patients with cancer diagnosed before and after IIM diagnosis remained uncertain. Methods: MyoHK was a longitudinal observational cohort that collected data from patients with rheumatologist diagnosis of IIM from 8 rheumatology centres in Hong Kong. Data were reviewed from 2004-2023 for this study. Patients with unavailable myositis specific antibody (MSA) were excluded from analysis. Occurrence of cancer 3 years before to 3 years after the diagnosis of IIM were documented. Patients with active cancer 3 years before diagnosis of IIM were classified to “Prior cancer” group and patients with cancer diagnosed at or within 3 years after IIM diagnosis were classified to “subsequent cancer” group. Patients were stratified to high, intermediate and standard cancer risks. Risk profile between the “prior cancer” and “subsequent cancer” groups were compared. Results: 501 patients were included in analysis. 82 patients had cancer within 3 years, in which 21 patients (25.6%) had cancer within 3 years preceding IIM diagnosis and 61 patients (74.4%) developed cancer at or within 3 years after IIM diagnosis. Nasopharyngeal, lung and breast cancers accounted for the top 3 cancers in both groups. In the “Prior cancer” group, patients were more likely to be female (85.7% vs 55.7%, p = 0.014) and were MSA-negative (33.3% vs 9.8%, p = 0.011). No patient in the “Prior cancer” group developed interstitial lung disease (0% vs 18.0%, p = 0.037) or fulfilled criteria for anti-synthetase syndrome (0% vs 13.1%, p = 0.062). Anti-TIF1g antibody was the most identified MSA in the two groups (42.9% vs 54.1%, p = 374). Myositis-associated-antibody (14.3% vs 42.6%, p = 0.019) and anti-Ro52 antibody (14.3% vs 37.7%, p = 0.047) were more common in the “subsequent cancer” group. In the overall cohort, 228 (45.5%), 246 (49.1%) and 27 (5.4%) of IIM patients were stratified into high, intermediate and standard cancer risk. Two-thirds of the “Prior cancer” group were stratified into high-risk while the remaining one-third being intermediate-risk, compared to 73.8% (p = 0.532) and 26.2% (p = 0.532) in the “subsequent cancer” group. Mortality between the two groups were comparable (38.1% vs 42.6%, p = 0.716). Conclusion: Compared to IIM patients with cancer detected at or after IIM diagnosis, patients with prior cancer were more likely to be female, negative for MSA and absence for ILD.

MDA5 Juvenile Dermatomyositis Misdiagnosed as Childhood Psoriasis: A Case Report

Juvenile Dermatomyositis (JDM) is a rare autoimmune disorder which mainly affects the skin and skeletal muscles. Characteristic features of this rare disorder include Gottron papules, heliotrope rashes and proximal muscle weakness. MDA5 positive JDM is usually associated with interstitial lung disease in later part of life. The authors report a case of an 11-year-old male child who presented to the Paediatric Department with complaints of rashes over extensor surfaces, Gottron papules and pain and weakness in all limbs. The child was on treatment from the Dermatology Department as a case of psoriasis for last six months. During hospital stay after detailed work-up, the child was diagnosed to have JDM. Anti-melanoma Differentiation-Associated gene 5 (Anti-MDA5) antibodies were positive in the present case. The child was treated with immunosuppressive drugs with supportive care and is currently on treatment for the last one and a half years and is largely asymptomatic. JDM requires meticulous clinical examination and specific investigations so that timely diagnosis can be made to ensure appropriate treatment. In the present index case, the authors describe the typical clinical presentation, newer investigative modalities like myositis specific antibody and treatment outcomes of this rare condition.

Autoantibody evaluation in idiopathic inflammatory myopathies.

Idiopathic inflammatory myopathies (IIM), generally referred to as myositis is a heterogeneous group of diseases characterized by muscle inflammation and/or skin involvement, diverse extramuscular manifestations with variable risk for malignancy and response to treatment. Contemporary clinico-serologic categorization identifies 5 main clinical groups which can be further stratified based on age, specific clinical manifestations and/or risk for cancer. The serological biomarkers for this classification are generally known as myositis-specific (MSAs) and myositis-associated antibodies. Based on the use of these antibodies, IIM patients are classified into anti-synthetase syndrome, dermatomyositis, immune-mediated necrotizing myopathy, inclusion body myositis, and overlap myositis. The current classification criteria for IIM requires clinical findings, laboratory measurements, and histological findings of the muscles. However, the use MSAs and myositis-associated autoantibodies as an adjunct for disease evaluation is thought to provide a cost-effective personalized approach that may not only guide diagnosis but aid in stratification and/or prognosis of patients. This review provides a comprehensive overview of contemporary autoantibodies that are specific or associated myositis. In addition, it highlights possible pathways for the detection and interpretation of these antibodies with limitations for routine clinical use.