To detect the expression levels of absence in melanoma 2 (AIM2), cysteine aspartate-specific protease-1 (caspase-1), and gasdermin D (GSDMD) in peripheral blood mononuclear cell (PBMC) of patients with idiopathic inflammatory myopathy (IIM) and to explore their role in the pathogenesis of IIM. A total of 30 IIM patients (IIM group) who visited the Department of Rheumatology and Immunology, General Hospital of Northern Theater Command from May 2020 to June 2022 were recruited. Concurrently, 30 healthy volunteers matched by gender and age were recruited from the hospital's Health Examination Center. Clinical information, biochemical and immunological mar-kers, and venous blood samples were collected from the study subjects. Serum double-stranded DNA (dsDNA) levels were detected by fluorescence quantitative method, and the mRNA expression levels of AIM2, caspase-1, GSDMD, interleukin 1β (IL-1β), and IL-18 in PBMC were detected by reverse transcription quantitative real-time PCR (RT-qPCR). The protein expression levels of AIM2, caspase-1, GSDMD, IL-1β, and IL-18 in PBMC were detected using the Western blot (WB) method, and the serum levels of IL-1β and IL-18 were detected by enzyme-linked immunosorbent assay (ELISA). The IIM group included 10 cases of dermatomyositis (DM), 5 cases of polymyositis (PM), 11 cases of overlap syndrome (OM), and 4 cases of immune-mediated necrotizing myopathy (IMNM). Compared with the healthy control group, the serum levels of dsDNA, IL-1β, and IL-18 were significantly increased in the IIM group and its subgroups (P < 0.05). Except for the fact that there was no statistically significant difference in AIM2 mRNA levels in PBMC of the IMNM subgroup compared to the healthy control group, the expression of AIM2, caspase-1, and GSDMD mRNA was significantly increased in the IIM group and other subgroups (P < 0.05); Except for the comparison of IL-1β mRNA levels in PBMC of the IMNM and OM subgroups with the healthy control group showing no statistical difference, the expression of IL-1β and IL-18 mRNA was significantly increased in the IIM group and other subgroups (P < 0.05); Comparisons between subgroups indicated that the expression of IL-1β mRNA in the DM subgroup was significantly higher than that in the OM and IMNM subgroups, and the expression of IL-18 mRNA in the PM subgroup was significantly higher than that in the DM and OM subgroups (P < 0.05). The expression levels of AIM2, caspase-1, GSDMD, IL-1β, and IL-18 proteins in PBMC of the IIM group and its subgroups were significantly higher than those in the healthy control group (P < 0.05); Comparisons among subgroups revealed that the expression of IL-18 protein in the OM subgroup was significantly higher than that in the PM subgroup (P < 0.05). In the IIM group, the mRNA of caspase-1, GSDMD, and IL-18 showed a positive correlation with AIM2 mRNA, and the protein expression of caspase-1, GSDMD, IL-1β, and IL-18 also showed a positive correlation with AIM2 protein expression. The AIM2 inflammasome-mediated pyroptosis pathway may be involved in the pathogenesis of IIM, providing a theoretical basis for further research on the etiology of IIM and the development of new therapies.

Baricitinib alleviates myositis-associated interstitial lung disease in mice by inhibiting the NETs-cGAS-STING-EMT axis.

To develop and validate data-driven algorithms for identifying patients with dermatomyositis (DM) and polymyositis (PM) using Japanese administrative claims data. This multicentre retrospective cross-sectional study included outpatients from six university hospitals between November and December 2023. Administrative claims data covering one year were linked with chart-confirmed diagnoses. Twenty-six candidate variables, including diagnosis codes, laboratory tests, prescriptions, and administrative billing items, were evaluated. Three feature-selection methods were applied to identify relevant predictors. Decision tree analysis was used to construct simplified rule-based algorithms, which were validated in independent internal and external cohorts. Among 8,199 training, 3,512 testing, and 1,827 external validation patients, 576 (7.0%), 244 (6.9%), and 136 (4.2%) carried diagnosis codes for DM/PM, of whom 352, 150, and 98 were confirmed as true cases, respectively. The performance of diagnosis codes alone yielded positive predictive values (PPVs) of 0.602 in the testing set and 0.713 in the external validation set. Anti-double-stranded DNA antibody testing, intractable disease management fees, and diagnosis codes for Sjögren's syndrome were identified as key discriminative variables. The optimal algorithm demonstrated sensitivity of 0.878, specificity of 0.984, PPV of 0.761, and F1-score of 0.815 in the external validation cohort, providing superior accuracy compared to the use of ICD-10 codes alone. ICD-10 codes alone were insufficient for accurate identification of DM/PM in Japanese claims data. Integrating laboratory tests and administrative information substantially improved PPV, providing a practical and generalizable framework for claims-based research in Japan.

Interleukin (IL)-38 has been recently identified as an anti-inflammatory cytokine. Polymyositis (PM) and dermatomyositis (DM) are two prevalent clinical inflammatory myopathies. This study aims to investigate the serum concentrations of IL-38 in patients with PM/DM and their association with these conditions. Serum IL-38 levels were quantified using the enzyme-linked immunosorbent assay method in a cohort of 117 subjects, comprising 77 patients with myositis (8 with PM and 69 with DM) and 40 healthy controls. A comprehensive assessment of preliminary clinical characteristics was conducted for each participant through physical examination and review of medical records. The diagnostic utility of IL-38 in PM/DM was evaluated using the receiver operating characteristic curve. The findings revealed that serum IL-38 concentrations were significantly elevated in patients with PM/DM compared to the control group, irrespective of the presence of interstitial lung disease. No significant difference was observed between the PM and DM groups. Furthermore, IL-38 demonstrated a positive correlation with the visual analogue scale, lactate dehydrogenase (LDH), and other inflammatory markers. Finally, IL-38, either independently or in conjunction with LDH, exhibits significant diagnostic potential. The study's findings reveal that patients with PM/DM who present elevated serum levels of IL-38 also show a positive correlation with LDH levels. This suggests IL-38 may participate in modulating inflammatory immune responses in PM/DM and could serve as a potential candidate indicator for these conditions.

A 52-year-old woman with myalgia, anti-aminoacyl tRNA synthetase, anti-SS-A/Ro52 antibody positivity, and elevated creatine kinase levels was admitted to our hospital. She was diagnosed with Sjögren's disease (SjD) complicated by polymyositis (PM). No chest symptoms were observed. Although her electrocardiogram and echocardiogram findings were normal, cardiac magnetic resonance imaging (CMRI) revealed myocardial edema and fibrosis with late gadolinium enhancement, elevated extracellular volume, and elevated T2 values. After treatment with prednisolone, the myalgia and CMRI abnormalities improved. This case suggests that CMRI may be useful for the detection and treatment of subclinical myocardial damage in patients with SjD complicated by PM.

Idiopathic inflammatory myositis (IIM), comprising polymyositis (PM) and dermatomyositis (DM), is a collective term for immune-mediated diseases characterized by skeletal muscle inflammation. Emerging evidence points to an increased incidence of epilepsy in patients with PM/DM. However, the causality and underlying mechanisms behind this association are unclear. Our study aimed to explore the potential causal link between PM/DM and epilepsy, with a focus on immune-mediated mechanisms, using Mendelian randomization (MR) and transcriptome analyses. Initially, summary data from genome-wide association studies (GWAS) related to polymyositis (PM; finn-b-M13_POLYMYO), dermatomyositis (DM; finn-b-DERMATOPOLY_FG), and epilepsy (ebi-a-GCST90018840) were obtained from the Integrative Epidemiology Unit Open GWAS database. These data were utilized for Mendelian randomization (MR) analysis and generalized summary data based Mendelian randomization (GSMR). To ensure the robustness of the findings, sensitivity analyses were conducted to corroborate the results of the MR analyses. Subsequently, the study leveraged publicly accessible databases and bioinformatics tools to conduct comprehensive analyses of gene expression data. This included differential expression analysis, immune infiltration analysis, and gene enrichment analysis. Differentially expressed SNP-related genes (DE-SRGs) were further analyzed using single-cell transcriptomics. Finally, the expression of four key genes (IER3, TNF, GPANK1, and ATF6B) in the hippocampus of epilepsy mouse model was quantified using PCR. The MR analysis disclosed a causal association between PM and epilepsy, whereas the reverse MR analysis did not identify a significant causal effect of epilepsy on PM. However, there was no association between DM and epilepsy of MR analysis. The Transcriptome analysis not only identified DE-SRGs but also revealed distinct immune cell infiltration patterns in epilepsy patients. Specifically, we observed SRGs are mainly expressed in endothelial cells, microglia, and T cells, indicative of a proinflammatory state. Furthermore, the gene set variation analysis (GSVA) highlighted the differential activation of pathways in these cell types, including inflammatory response and allograft rejection, which were significantly upregulated. PCR results show the expression of IER3, TNF, GPANK1, and ATF6B in hippocampus of epilepsy model largely consistent with bioinformatics predictions. The study reveals a causal association between PM and epilepsy, with no significant impact of epilepsy on PM. There is no causal association between DM and epilepsy. The absence of a DM-epilepsy link may reflect fundamental differences in immunopathology: while PM is driven by T cell-mediated muscle invasion, DM involves predominant humoral immunity and complement deposition, suggesting distinct neuroinflammatory implications. Our findings establish immune-mediated neuroinflammation as the central mechanistic link between PM and epileptogenesis. These findings implicate shared immunopathogenic mechanisms and suggest therapeutic targets for epilepsy associated with polymyositis.

Neuromyelitis optica spectrum disorder (NMOSD) is an autoimmune inflammatory demyelinating disease primarily affecting the optic nerves and spinal cord. Polymyositis (PM) is an idiopathic inflammatory myopathy characterized by proximal muscle weakness. The anti-signal recognition particle (SRP) antibody is a myositis-specific autoantibody. We herein present a case of anti-SRP antibody-positive PM that developed 6years after the onset of NMOSD. A 52-year-old woman was diagnosed with NMOSD 6years previously based on left visual disturbance, a high signal intensity and contrast enhancement of the optic nerve on short τ inversion recovery (STIR)-magnetic resonance imaging (MRI), and anti-aquaporin 4 antibody positivity. She received methylprednisolone pulse therapy followed by oral prednisolone (PSL) at a starting dose of 40mg daily. Three years later, due to recurrent numbness in the left lower limb and difficulty in reducing the PSL dose to ≤10mg/day, satralizumab was initiated. At 52years old, she developed myalgia and muscle weakness in both thighs. PM was diagnosed based on an elevated serum creatine kinase level, anti-SRP antibody positivity, high signal intensities in the right triceps and bilateral adductor muscles on STIR-MRI, and muscle biopsy findings. Treatment with high-dose PSL and tacrolimus markedly attenuated her symptoms. Satralizumab was continued for NMOSD stabilisation. Previous studies reported the coexistence of NMOSD and autoimmune diseases; however, NMOSD with PM/DM is rare. We described a case of NMOSD with anti-SRP antibody-positive PM and provided a literature review.

Idiopathic inflammatory myopathies (IIM) are rare autoimmune disorders primarily affecting skeletal muscles, with occasional involvement of other organs and an increased risk of malignancy. Dermatomyositis (DM), a major IIM subtype, is characterized by proximal muscle weakness, distinctive skin manifestations, and characteristic biopsy findings. Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitides (AAV), including microscopic polyangiitis (MPA), involve small- to medium-sized vessels and can affect the kidneys and lungs. Although uncommon, overlap syndromes between IIM and AAV have been described. We report two cases of DM-MPA overlap. The first involved a 67-year-old male with interstitial lung disease (ILD), muscle weakness, and proteinuria. The second concerned a 53-year-old female presenting with characteristic skin rash, arthralgias, proteinuria, and mild pulmonary involvement. Both patients received high-dose corticosteroids and cyclophosphamide (CYC), resulting in clinical and laboratory improvement, including resolution of proteinuria and improved pulmonary function, maintained over a 6-month follow-up. The literature review identified five relevant case reports and one case series. Fifteen patients from these six studies were included, predominantly female (13/15), with ages ranging from 15 to 84 years. DM was the most common IIM subtype (7/15), followed by polymyositis (PM) (6/15), inclusion body myositis (IBM) (1/15), and clinically amyopathic dermatomyositis (CADM) (1/15). MPA accounted for 87% (13/15) of AAV cases, while GPA was reported in 2/15. Renal involvement was frequent, often presented as pauci-immune crescentic glomerulonephritis, whereas pulmonary involvement was less common. MPO-ANCA was positive in 12/15 patients. Initial therapy typically involved corticosteroids, with or without immunosuppressants, tailored according to the dominant organ involvement. Outcomes were variable; most patients achieved remission, although some experienced persistent organ dysfunction. IIM-AAV overlap is rare but potentially severe, frequently involving renal, pulmonary, muscular, and occasionally cardiac systems. Early recognition and individualized immunosuppressive therapy can yield favorable outcomes. Multicenter studies are required to clarify the epidemiology, clinical spectrum, and optimal management of this complex syndrome, and further research is needed to elucidate underlying pathogenic mechanisms.

Overall and by subtype epidemiology of idiopathic inflammatory myopathies among African descent patients with free access to high standard healthcare.

Identification of idiopathic inflammatory myopathy research cohorts using international classification of disease (ICD) codes: A systematic review.

Unveiling IL-41: A novel biomarker for polymyositis and dermatomyositis diagnosis.

Background. Idiopathic inflammatory myopathies (IIM) are a group of rare and heterogeneous diseases. One of the greatest challenges in IIM management is defining and predicting disease flares, which are inconsistently characterized across studies. The aim of the study was to identify predictors of relapse in a retro-prospective, multi-centric IIM cohort during the first two years of disease. Methods. Patients with IIM subsets—dermatomyositis (DM), polymyositis (PM), anti-synthetase syndrome (ASyS), connective tissue disease-associated IIM (CTD-IIM), or immune-mediated necrotizing myopathy (IMNM)—were included if &gt;=18 yrs and with &gt;= 2 years of follow-up. Relapse was defined as a change in disease activity requiring escalation of immunosuppressive therapy and/or steroids. Patients were classified as monocyclic (no relapse in the first 2 years), polycyclic (&gt;=1 relapse in the first 2 years), or chronic continuous. Clinical characteristics across subgroups were compared using chi-square, Mann–Whitney U, or Student’s t-test. Predictors were identified through multivariable logistic regression. Results. Of 297 screened patients, 91 were excluded due to missing data. A total of 206 patients were included (155 female; median age at diagnosis 46.9 years). 82 (39.8%) were DM, 56 (27.2%) ASyS, 40 (19.4%) CTD-IIM, 14 (6.8%) PM, and 14 (6.8%) IMNM. During the first 2 years of disease, 84 patients (40.8%) had monocyclic course, 67 (32.5%) polycyclic course, and 55 (26.7%) chronic continuous course. No significant differences in disease course distribution were observed across IIM subsets, although PM and IMNM were more frequently associated with chronic or relapsing patterns (64.2% vs. 35.8%). Myositis autoantibodies were not significantly linked to any disease course. Relapses occurred despite stable treatment for over one year in approximately one-third of cases. Most relapses involved muscle (61.9%), particularly in PM/IMNM (89%), whereas the frequency was notably lower in ASyS (43.2%), where ILD was the leading cause of relapse (61.4%). Refractory disease was the predominant phenotype in PM/IMNM (55.6%) and ASyS (52.3%), while drug tapering was most frequent cause implicated in DM (30%) and CTD-IIM (31%). Muscle and cardiac involvement at baseline were less frequent in monocyclic patients. A more severe disease phenotype—reflected by higher levels of muscle enzymes, and both PtGA and PhGA—was more commonly associated with non-monocyclic disease. Notably, non-monocyclic patients had received baseline low-dose steroids (&lt;0.25 mg/kg; 78.9% vs. 21.1%, p = 0.019) and intravenous immunoglobulins (10.0% vs. 26.0%, p = 0.004). Multivariable analysis confirmed baseline muscle involvement, CK levels, and PtGA as independent predictors of relapse. - Conclusions. In this large, diverse IIM cohort, non-monocyclic disease (polycyclic and chronic continuous) was associated with baseline myositis, higher serum muscle enzymes, higher global activity scores, and lower steroid induction dosage. These findings highlight the potential value of flare predictors and advocate for standardized definitions of disease activity/relapse in IIM.

Background. Idiopathic inflammatory myopathies (IIM) are a group of autoimmune diseases characterized by inflammation of the muscle with clinical manifestations such as skin rash, interstitial lung disease, heart involvement or arthritis. Within IIM, we distinguish dermatomyositis (DM), immune-mediated necrotizing myopathy (IMNM), anti-synthetase syndrome (ASyS), inclusion body myositis (IBM), and Polymyositis (PM). Nailfold video-capillaroscopy (NVC) is a useful technique to study microvascular abnormalities in autoimmune diseases and a scleroderma-like (SL) pattern has been reported in about 70% of DM patients and in 35% of those with ASyS. Histologically, muscular findings are shared across IIM subgroups, such as sarcolemmal expression of MHC I and inflammatory infiltrates. Others are more specific: perifascicular atrophy (PFA) in DM or perifascicular necrosis (PFN) in ASyS. The aim of our study was to evaluate qualitatively and quantitatively the capillaroscopic alterations in IIM patients, for their possible associations with histological data. Materials and Methods. Patients with IIM who underwent muscle biopsy and NVC were prospectively enrolled. Morphological parameters were assessed qualitatively (number, length, distribution, and size of capillary loops, as well as microhemorrhages and neoangiogenesis). We also assigned a semiquantitative score (0–3) and other quantitative scores (total megacapillary count, mean of megacapillaries apex width, mean capillary density, number of hemorrhages, and mean of avascular areas). Results. We enrolled 20 patients including 9 with DM, 4 with ASyS, and 7 with PM. Table 1 presents the main clinical, histological, and capillaroscopic features of our cohort. Regarding capillaroscopic findings, we observed a significant association between the presence of a SL pattern and DM diagnosis (p=0.0098). Comparing the biopsies regardless of the type of idiopathic inflammatory myopathy (IIM), we observed a higher mean semiquantitative score in patients exhibiting perifascicular fiber hypotrophy compared to those without (mean 2, IQR 0–2 vs mean 0, IQR 0–1;p=0.0359), as well as a significant association with the presence of an SL pattern (p=0.0246). This group of patients also showed a marked reduction in capillary density (p=0.0190) and an increased mean number of avascular areas (p=0.0058). ASyS patients displayed a significant association with perifascicular necrosis (p=0.0010), consistent with previous reports, but also with perifascicular fiber hypotrophy (p=0.0260), whereas we did not confirm the described association with DM. Conclusions. To our knowledge, this study is the first to explore the relationship between NVC findings and muscle biopsy features in IIM patients using both qualitative and quantitative methods. Our data suggest a link between perifascicular muscle fiber hypotrophy—where muscle vasculature damage is believed to originate—and specific capillaroscopic abnormalities in DM and ASyS cases. Expanding our understanding of the underlying peripheral vasculopathy in the different forms of IIM requires a larger patient cohort and a deeper histological evaluation of muscular and vascular injury.

The Mythology of Polymyositis.

Anti-MDA5 autoantibodies are critical biomarkers for dermatomyositis (DM), amyopathic dermatomyositis (CADM), and polymyositis (PM), particularly in identifying patients at risk of rapidly progressive interstitial lung disease (RP-ILD). Early detection of these autoantibodies is essential to improve patient outcomes, as delayed diagnosis often leads to poor prognoses. Currently, radioimmunoassay is the gold standard for detecting anti-MDA5, but its use is limited by high costs, lengthy procedures, and the need for specialized expertise. Additionally, the blot test, a widely used clinical tool, exhibits a high false-positive rate for MDA5 autoantibodies, potentially compromising diagnostic accuracy. To address these limitations, we propose a non-radioactive, highly sensitive, and standardized confirmatory testing method using Immunocytochemistry (ICC). This protocol involves treating HeLa cells with an MDA5 construct, permeabilizing the cells with Triton X-100 to facilitate binding of primary anti-MDA5 autoantibodies, and detecting bound antibodies using enzyme-conjugated secondary antibodies (e.g., horseradish peroxidase) with DAB chromogen for microscopy imaging. ICC offers a practical, cost-effective, and high-sensitivity approach for visualizing anti-MDA5 autoantibodies within cellular structures. By integrating ICC as a supplementary confirmatory procedure, this study aims to enhance the reliability of anti-MDA5 detection, thereby improving diagnostic and prognostic strategies for RP-ILD in DM, CADM, and PM patients.

Background/Objectives: The epidemiology of dermatomyositis (DM) and other idiopathic inflammatory myopathies (IIMs) remains not well established, especially in the Mediterranean region. We aimed to estimate the prevalence and incidence of IIM in a well-defined population of South Europe using standardized classification criteria. Methods: This population-based study included all IIM patients diagnosed from January 2000 to December 2022 in Cantabria, Northern Spain. IIM diagnosis was confirmed by fulfillment of the 2017 EULAR/ACR classification criteria or, alternatively, by European Neuro Muscular Center criteria for immune-mediated necrotizing myopathy (IMNM) and Connors’ criteria for antisynthetase syndrome (ASyS). Prevalence and incidence were expressed in cases per 100,000. A literature review was also performed. Results: A total of 60 patients (41 women, 19 men; mean age 52.6 ± 18.8 years) were included. The prevalence of IIM was 20 cases per 100,000 population [95% CI 14.5–25.1], and the annual incidence rate was 0.9 cases per 100,000 person-years [95% CI 0.6–1.14]. A significant upward trend in IIM incidence was observed with an estimated annual percentage change of 5.74% (95% CI: 2.16%–9.44%, p = 0.0015). The most common subtype was DM (n = 31, 51.7%), followed by ASyS (n = 17, 24%), IMNM (n = 9, 14.6%), and polymyositis (PM) (n = 3, 4.7%). No inclusion body myositis (IBM) cases were identified. Conclusions: Incidence and prevalence of IIM align with prior reports. We observed an increase in IIM incidence and a shift in subtype distribution, with ASyS and IMNM becoming more frequent. These findings have clinical relevance, as each IIM subtype carries distinct prognostic and therapeutic implications.

Introduction: Polymyositis (PM), a pathological condition marked by the presence of inflammatory infiltrates in striated muscle. Develops with the main clinical sign as Proximal muscular weakness. Though its exact aetiology is uncertain, it appears to be an autoimmune condition. It can affect persons at any age, but typically manifests between 50 to 70 years of age. It is twice as common in women as in men and exists in one out of every 100,000 people. Ayurveda categorizes its symptoms under "mamsagata vata", as musculoskeletal abnormality. Currently, there's no known cure, but conventional treatment often involves corticosteroids, which can have adverse effects on long use. Materials and Methods: This is an interesting case study demonstrating the successful management of female patient of age 58 years, suffering from Polymyositis (mamsagata vata). As it is possible for such muscle weakness to appear suddenly or more subtly over several weeks or months; similarly for this case it took several months to manifest and get diagnosed. After many unsatisfactory contemporary treatments patient approached to ayurveda and hence, the combination of Ayurvedic modalities such as Udvartana, Abhyanga, Basti, Oral medications, Physiotherapy were administered for 5 months involving IPD and OPD sittings. Results: Treatments contributed in the improvement of Gait, Muscle power, tone and Overall strength. Aided in the gradual reduction and eventual cessation of medications such as Mycophenolate Mofetil and Prednisolone, while effectively managing symptoms and significantly lowering the Creatine Phosphokinase (CPK) level. Conclusion: This case underscores the effectiveness of Ayurvedic treatments in addressing autoimmune conditions such as polymyositis.

T2 weighted magnetic resonance imaging has become a commonly used noninvasive examination method for the diagnosis of Polymyositis (PM). The data regarding the comparison of deep learning and radiomics in the diagnosis of PM is still lacking. This study investigates the feasibility of 3D convolutional neural network (CNN) in the prediction of PM, with comparison to radiomics. A total of 120 patients (with 60 PM) were from center A, and 30 (with 15 PM) were from B, and 46 (with 23 PM) were from C. The data from center A was used as training data, and data from B as validation data, and data from C as external test data. The magnetic resonance radiomics features of rectus femoris were obtained for all cases. The maximum correlation minimum redundancy and least absolute shrinkage and selection operator regression were used before establishing a radiomics score model. A 3D CNN classification model was trained with “monai” based on 150 data with labels. A 3D Unet segmentation model was also trained with “monai” based on 196 original data and their segmentation of rectus femoris. The accuracy on the external test data was compared between 2 methods by using the paired chi-square test. PM and non-PM cases did not differ in age or gender (P > .05). The 3D CNN classification model achieved accuracy of 97% in validation data. The sensitivity, specificity, accuracy and positive predictive value of the 3D CNN classification model in the external test data were 96% (22/23), 91% (21/23), 93% (43/46), and 92% (22/24), respectively. The radiomics score achieved accuracy of 90% in the validation data. The sensitivity, specificity, accuracy, and positive predictive value of the radiomics score in the external test data were 70% (16/23), 65% (15/23), 67% (31/46), and 67% (16/24), respectively, significantly lower than that of CNN model (P = .035). The 3D segmentation model for rectus femoris on T2 weighted magnetic resonance images was obtained with dice similarity coefficient of 0.71. 3D CNN model is not inferior to radiomics score in the prediction of PM. The combination of deep learning and radiomics is recommended for the evaluation of PM in future clinical practice.

Background: Interstitial lung disease (ILD) is a major extra-muscular manifestation of dermatomyositis (DM) and polymyositis (PM), yet data from Middle Eastern populations remain sparse. We aimed to characterize radiologic ILD patterns, severity, clinical–serologic correlates, and treatment usage among Saudi patients with PM/DM-ILD managed at a tertiary center. Methods: We conducted a retrospective cohort study (2006–2022) at a single tertiary hospital in Riyadh, Saudi Arabia. Adult patients (≥18 years) with PM/DM by 2017 ACR/EULAR classification were re-adjudicated, and ILD was confirmed by high-resolution CT (HRCT) after blinded re-review by a thoracic radiologist. ILD patterns followed ATS/ERS categories (NSIP, UIP, OP, RB-ILD, unclassifiable). Severity was treated separately from pattern and operationalized as “mild” if HRCT parenchymal involvement was &lt;20% or, when imaging was equivocal, if FVC ≥80% predicted. Demographics, clinical features, standard serologies, pulmonary function tests (PFTs), echocardiography, and treatments were abstracted using a standardized form with double-entry checks. Analyses were descriptive and exploratory; between-group comparisons were limited to subgroups with n≥5 and adjusted for multiple testing (Holm). Results: Thirty-five patients met criteria (80% female; DM 60%, PM 40%). On HRCT rereview, NSIP was the most frequent pattern (37.1%, 13/35), followed by unclassifiable (14.3%, 5/35), UIP (5.7%, 2/35), RB-ILD (2.9%, 1/35), and OP (2.9%, 1/35). In parallel, severity was mild in 37.1% (13/35) across patterns. ILD timing relative to myositis was PM/DM-preceding in 48.6%, concomitant in 31.4%, and ILD-preceding in 20%. Exertional dyspnea (74.3%) and non-productive cough (62.9%) were frequent; heliotrope rash and Gottron papules each occurred in 34.3%. ANA was positive in 82.9%; anti-Jo-1 in 34.3%. FVC (mean ± SD) approximated 71% predicted overall; DLCO ~90% predicted where available. As pre-specified, no inferential tests were performed for subgroups with n&lt;5 (UIP, RB-ILD, OP), and signals from small cells were treated descriptively only. Glucocorticoids were universally used; 77.1% were maintained at ≤7.5 mg/day. Mycophenolate mofetil (54.3%) and rituximab (48.6%) were the most common steroid-sparing agents; azathioprine (40%), methotrexate (34.3%), and IVIG (25.7%) were also used; antifibrotics were prescribed in 11.4%. Conclusion: In this Saudi tertiary-care cohort, NSIP predominated as the ILD pattern, while mild severity at presentation was common but distinct from pattern. The dataset underscores heterogeneity in serology and treatment and highlights the need for standardized radiologic severity grading, prospective PFT capture, and multicenter registries to refine prognosis and guide therapy in regional PM/DM-ILD.

ObjectivesTo estimate shared genetic susceptibility between major subtypes of idiopathic inflammatory myopathies (IIM) and B cell lymphomas.MethodsWe paired summary statistics from genome-wide association studies (GWASs) of diffuse large B cell lymphoma, follicular lymphoma (FL), chronic lymphocytic leukaemia (CLL) and marginal zone lymphoma with those of dermatomyositis (DM) and polymyositis (PM) from a GWAS and an ImmunoChip study. We estimated local genetic correlation (rg) for each disease pair using local analysis of (co)variant association (Bonferroni-corrected p value<0.05) and identified genetic variants jointly associated with both diseases using pleiotropy-informed false discovery rate (conjunctional false discovery rate <0.05). Functional mapping and annotation analyses were also performed.ResultsWe identified significant rg (ranging from −0.50 to 0.84) across 16 loci, with half located in the human leucocyte antigen (HLA) region, for the disease pairs of IIM and B cell lymphoma subtypes. Furthermore, jointly associated single-nucleotide polymorphisms were predominantly found in the HLA region. Specifically, all disease pairs showed shared genetic susceptibility in the HLA class I regions, while additional correlations in class III and class II regions were specific to DM and PM disease pairs, respectively. For some non-HLA loci with significant rg, functional analyses revealed immune-related responses potentially overlapping between DM and FL, DM and CLL, and PM and CLL.ConclusionWe revealed that DM and PM share genetic susceptibility with common B cell lymphoma subtypes in both immune-related loci and loci with unclear biological functions. These novel findings improve our understanding of the pathological link between IIM and B cell lymphomas.