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Interstitial lung disease (ILD) is a common and serious manifestation of autoimmune rheumatic diseases. While the prevalence of ILD differs among the individual autoimmune rheumatic diseases, ILD remains an important cause of morbidity and mortality in systemic sclerosis, systemic lupus erythematosus, mixed connective tissue disease, primary Sjögren's disease, rheumatoid arthritis, and idiopathic inflammatory myositis. The present review summarizes recent literature on autoimmune-associated ILD with a focus on screening and monitoring for ILD progression. Reflecting on the currently available evidence, the authors propose a guideline for monitoring for progression in patients with newly diagnosed autoimmune-associated ILD. This review also highlights clinical and biological predictors of progressive pulmonary fibrosis and describes opportunity for further study in the rapidly evolving area of rheumatology and pulmonology.

La enfermedad pulmonar intersticial (EPI) es una manifestación común y seria de las enfermedades autoinmunes. Aunque la prevalencia de EPI difiere de acuerdo a cada enfermedad, continúa siendo una causa importante de morbilidad y mortalidad en la esclerosis sistémica, la artritis reumatoide, el síndrome de Sjögren, la enfermedad mixta del tejido conjuntivo y las miopatías inflamatorias. Este artículo de revisión resume la literatura reciente sobre la EPI asociada con autoinmunidad, con enfoque en la búsqueda y el monitoreo de la progresión de la EPI. Con base en la evidencia disponible, los autores proponen una guía para el monitoreo de la progresión en pacientes con la EPI asociada con autoinmunidad de reciente diagnóstico. Esta revisión también aborda los predictores clínicos y biológicos de la fibrosis pulmonar progresiva y resalta la oportunidad para estudios adicionales en áreas de rápida evolución como la reumatología y la neumología.

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BACKGROUND: COVID-19 can induce a systemic inflammatory response with variable clinical manifestations. Similar to various viruses, COVID-19 has been implicated in the pathogenesis of autoimmune diseases. This article highlights the potential for infections including the SARS-CoV-2 virus to induce exacerbations of pre-existing autoimmune diseases or even potentially unmask de novo autoimmune diseases in particular anti-synthetase syndrome (ASSD) in predisposed individuals. Although there are other case reports of ASSD following SARS-CoV-2 infection, here we present the first reported case of a gentleman with a newly diagnosed anti-OJ positive anti-synthetase syndrome following SARS-CoV-2 infection. CASE PRESENTATION: Described is a case of a 70-year-old man presenting to the emergency department with worsening dyspnea in the context of a recent COVID-19 infection. CT-chest revealed changes suggestive of fibrotic lung disease, consistent with usual interstitial pneumonitis (UIP) pattern. Despite recovery from his COVID-19 illness, the patient subsequently developed proximal myopathy with cervical flexion weakness on further assessment with persistently elevated creatinine kinase (CK). Myositis autoantibodies found a strongly positive anti-OJ autoantibody with MRI-STIR and muscle biopsy performed to further confirm the diagnosis. The patient received pulse methylprednisolone 1 g for 3 days with a long oral prednisolone wean and in view of multiple end-organ manifestations, loading immunoglobulin at 2 g/kg administered over two days was given. In addition, he was then commenced and escalated to a full dose of azathioprine given a normal purine metabolism where he remains in clinical remission to this date. At least 267 cases of rheumatic diseases has been associated with SARS-CoV-2 infection as well as COVID-19 vaccination. A literature search on PubMed was made to determine the amount of case reports describing myositis associated with SARS-CoV-2 infection. We found 3 case reports that fit into our inclusion criteria. Further literature searches on diagnostic approach and treatment of ASSD were done. CONCLUSION: Although SARS-CoV-2 infection itself can cause a directly mediated viral myositis, this case report highlights the possibility of developing virus-triggered inflammatory myositis through multiple aforementioned proposed mechanisms. Therefore, further studies are required to explore the relationship and pathophysiology of SARS-CoV-2 infection and the incidence of inflammatory myopathies.

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Kikuchi-Fujimoto disease (KFD) is a benign, self-limiting histiocytic necrotizing lymphadenitis systemic disorder with unknown etiology. KFD has been known for half a century, but difficulties in distinguishing it remain. Its diagnostic significance is related to the increasing prevalence of KFD with autoimmune diseases in various timeframes. Systemic lupus erythematosus (SLE) is the most prevalent autoimmune connective tissue disease (AICTD) appearing alongside KFD. An 18-year-old female presented with acute muscle weakness, shortness of breath, fever, and significant weight loss for 5 months before admission. Pain and morning joint stiffness had been felt for 9 months. One year ago, she lumped her right neck and was diagnosed with KFD from the excision biopsy and immunohistochemical staining (CD68). Creatine-kinase enzymes and C-Reactive protein were elevated with a high anti-Ku and anti-Jo-1 negative level. There was a low level of complements, high anti-nuclear antibody titer, with positive anti-SS-A. Sialometry and Schirmer test showed reduced salivary and lacrimal gland production. We diagnosed this patient as having an overlap syndrome preceded by KFD. The AICTD involved was Sjögren's syndrome and SLE. Although KFD is considered a self-limiting disease, its occurrence should be noticed regarding the possibility of other autoimmune conditions. KFD usually coincides with AICTD, although it could also precede or occur afterward. This case is reported to raise awareness of the overlap syndrome preceded by KFD.

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Disease manifestations of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV), a small vessel vasculitis with multisystemic effects, include respiratory, renal, nervous, gastrointestinal, and skin implications. Muscle weakness and inflammatory myopathy are rare manifestations of AAV. We report the case of a 77-year-old female with a medical history of hypothyroidism and osteoarthritis who presented with a two-month history of worsening muscle weakness (mainly proximal). She endorsed dysphagia, a 40-lb unintentional weight loss, and persistent sinusitis with middle ear effusions, requiring bilateral tympanostomy. The physical examination was notable for 2/5 muscle strength in her hip flexors and extensors, with 4/5 strength in other extremities. Lower extremity MRI showed diffuse intramuscular edema between fat planes and intramuscular septal regions. Erythrocyte sedimentation rate (70 mm/hr), C-reactive protein (141 mg/L), creatine kinase (690 U/L), and anti-myeloperoxidase (MPO) antibodies (>999 AU/mL) were elevated. A thigh biopsy revealed fibrinoid necrosis of small intramuscular arteries, confluent circumferential granulomatous vessel wall inflammation, and associated mild chronic inflammation, including occasional eosinophils and a few plasma cells. She was diagnosed with MPO-positive AAV. The patient was started on high-dose steroids (prednisone), with a taper on a disease-modifying agent, azathioprine, with significant improvement in symptoms over the next four months and complete resolution at 16-month follow-up. This patient's clinical presentation of predominant lower extremity weakness due to inflammatory myositis is an unusual manifestation of AAV. Clinicians should keep a broad differential diagnosis and consider the possibility of AAV, especially in cases of muscle weakness presenting as inflammatory myositis, in the absence of other clinical manifestations of systemic vasculitis or specific myositis serologies.

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Dermatomyositis is a rare, autoimmune systemic disorder of unknown aetiology that presents as a constellation of clinical symptoms and signs primarily affecting skin and muscles. Patients with dermatomyositis can present with rare "non-canonical" manifestations. Focal or generalised oedema is an infrequent and often overlooked symptom of the disease, while spontaneous intramuscular haemorrhage is an even rarer and under-recognised, life-threatening complication that constitutes a medical emergency for clinical physicians. There are no known predisposing factors able to predict which patients will develop this complication and specific instructions considering treatment approach are currently lacking. Herein, we present a case of a patient with dermatomyositis complicated by both anasarca and spontaneous intramuscular haemorrhage. In order to raise awareness and timely diagnosis of such patients, we provide a review of the relevant literature and of the cases reported this far.

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This study investigated the clinical features and prognostic relevance of decreased serum complement levels in patients with idiopathic inflammatory myositis (IIM). The clinical information of IIM patients with less than normal serum complement levels (L-Com) and that of those with normal serum complement levels (N-Com) was compared. In patients with interstitial lung disease (ILD), regression analyses were used to investigate the implication of L-Com in their PaO2/FiO2 (P/F) ratio. Prognostic outcomes of ILD were evaluated using the log-rank test. Of 94 IIM patients, 26 with L-Com (median age, 56.0 years) and 68 with N-Com (56.5 years) were included. The prevalence of women was significantly higher in patients with L-Com (92.3%) than in those with N-Com (67.6%). ILD was observed in 17 (65.4%) patients with L-Com and in 46 (67.6%) with N-Com. Among patients with ILD, the P/F ratio was significantly lower in those with L-Com than in those with N-Com. Serum C3 levels were correlated with decreased P/F ratio. Inferior prognosis of ILD was significantly demonstrated in patients with L-Com, especially in those positive for anti-melanoma differentiation-associated protein 5 antibody. L-Com may be implicated in reduced arterial oxygen levels and a poorer prognosis in patients with IIM-related ILD.

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OBJECTIVES: To find out if Rituximab (RTX) is effective in "treatment naive" idiopathic inflammatory myopathies (IIM), and whether there could be differential treatment responses between the "treatment naive" and treatment "refractory" IIM. METHODS: Data obtained from a prospectively maintained database comprising patients with IIM treated with rituximab. Patient details were obtained at baseline, 3-months, 6-months intervals, and subsequent follow up visits. Treatment response was categorised as improved, worsening, or stable based on manual muscle testing (MMT8) scores, patient global and physician global improvement (PtGA and PGA) for skin and joint symptoms improvement and spirometry at 6 months. The time to clinical improvement and remission were noted and survival analysis curves were constructed. RESULTS: 60 patients with IIM (including 18 with anti-SRP myopathy) were included, out of which 33 who received RTX were treatment naïve. The remaining 27 were started on rituximab for refractory myopathy. Mean age was 39 years (SD12.58) in "treatment-naive" group and 43 years (SD 12.12) in "refractory" group. At 6 months of follow up, 48/55 (87%) patients showed response, 31/31 (100%) in "treatment-naive" and 17/24 (70%) in "refractory" cases, p 0.006*. In refractory group, 7 (29%) had stable disease. The mean changes in MMT8 were significantly more in the "treatment-naive" treatment group (13.41(SD 7.31) compared with "refractory" IIM 8.33 (SD 7.92) (p= 0.017*). Majority of patients were able to reduce dose below 5 mg/day before 6 months. No major adverse events were reported over the median follow-up of 24 (IQR 36) months. CONCLUSIONS: Rituximab is effective and safe across the spectrum of IIM. Early use in disease is associated with better outcomes.

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Idiopathic inflammatory myopathies (IIM) are a group of myopathies that present with muscle weakness and multiple extra-muscular manifestations, in which lymphocytes play central roles in myositis pathogenesis. This study aimed to explore the clinical characteristics of lymphocyte subsets, especially B cell subsets, in patients with IIM. Our study included 176 patients with active IIM and 210 gender/age-matched healthy controls (HCs). Compared to HCs, patients have reduced counts of T cells, B cells, and natural killer cells. In addition, B cell subsets from 153 patients with IIM and 92 HCs were characterized. Patients had a lower percentage of memory B cells and translational memory B cells, while those patients were with an elevated percentage of CD19+ B cells, plasmablast and naïve B cells compared with HCs. Moreover, to further explore the heterogeneity of B cells in IIM, patients were categorized into three clusters based on clustering analysis. Cluster 1 was dominated by CD19+ B cells, Bregs and naïve B cells, cluster 3 was dominated by memory B cells and plasmablast, and cluster 2 had the highest proportion of translational memory B cells. Notably, patients in cluster 1 presented with higher CK levels, indicating muscle damage, whereas patients in cluster 3 showed a higher incidence of chest tightness. Our study indicated that lymphopenia is a common manifestation in patients with IIM. B cell subsets are abnormally expressed and showed high heterogeneity in patients with IIM. The patients with IIM were divided into three different clusters with different percentages of chest tightness and distinct CK levels.

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BACKGROUND: Idiopathic inflammatory myopathies (IIMs) are a group of autoimmune disorders often complicated by interstitial lung disease (ILD). The clinical characteristics and outcomes of IIM-associated ILD have been reported variably, but the literature on rural populations is scarce. METHODS: A retrospective cross-sectional study was conducted at a rural tertiary academic medical center. Twenty-nine patients met the final inclusion criteria. The primary outcome was to assess the disease state and immunological and radiographic features of IIM-associated ILD. Secondary outcomes included disease progression, ILD exacerbation, mortality rate, and factors associated with poor outcome. RESULTS: Dermatomyositis (n = 15, 51.72%) followed by polymyositis (n = 8, 27.58%) were predominant myopathies. The most common autoantibodies were anti-Jo1 antibodies (n = 11, 37.93%). Indeterminate usual interstitial pneumonitis (41.30%, n = 12) was the most common radiographic pattern followed by non-specific interstitial pneumonia (n = 5, 17.24%). ILD exacerbation (n = 14, 66.66%) and mortality rate (n = 6, 20.69%) were high. Albumin levels were significantly lower in patients who died. CONCLUSIONS: The clinical characteristics of patients with IIM-associated ILD in rural Appalachia exhibit notable distinctions, and outcomes are worse compared to other populations. Larger studies are needed to investigate other prognostics factors and longitudinal trends of clinical characteristics and outcomes of IIM-associated ILD in rural populations.

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Statins can commonly cause myopathy. Most of the time, stopping the culprit drug should solve the problem. However, if the drug has been discontinued but muscle weakness continues to worsen, immune-mediated myopathy should be taken into consideration.

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OBJECTIVES: Myositis-specific and associated autoantibodies are important biomarkers in routine clinical use. We assessed local testing performance for myositis autoantibodies by comparing line immunoassay (LIA) to protein radio-immunoprecipitation and identifying clinical characteristics associated with each myositis autoantibody in the MyoCite cohort. METHODS: Serum samples from patients within the MyoCite cohort, a well-characterized retro-prospective dataset of adult and juvenile idiopathic inflammatory myopathy (IIM) patients in Lucknow, India (2017-2020), underwent LIA at Sanjay Gandhi Postgraduate Institute of Medical Science (SGPGIMS), Lucknow. Immunoprecipitation of 147 IIM patients' serum samples (125 adult-onset, 22 juvenile-onset) was conducted at the University of Bath, with researchers blind to LIA results. LIA performance was assessed against immunoprecipitation as the reference standard, measuring sensitivity, specificity and inter-rater agreement. Univariate and multivariate logistic regression determined clinical associations for specific myositis-specific autoantibodies. RESULTS: Immunoprecipitation identified myositis autoantibodies in 56.5% (n = 83) of patient samples, with anti-Jo1 (n = 16; 10.9%) as the most common, followed by anti-MDA5 (n = 14, 9.5%). While LIA showed good agreement for anti-Jo1, anti-PL7 and anti-PL12 (Cohen's κ 0.79, 0.83 and 1, respectively), poor agreement was observed in other subgroups, notably anti-TIF1γ (Cohen's κ 0.21). Strongly positive samples, especially in myositis-specific autoantibodies, correlated more with immunoprecipitation results. Overall, 59 (40.1%) samples exhibited non-congruence on LIA and immunoprecipitation, and κ values for LIAs for anti-TIF1γ, anti-Ku, anti-PmScl, anti-Mi2 and anti-SAE ranged between 0.21 and 0.60. CONCLUSION: While LIA reliably detected anti-Jo1, anti-PL7, anti-PL12, anti-MDA5 and anti-NXP-2, it also displayed false positives and negatives. Its effectiveness in detecting other autoantibodies, such as anti-TIF1γ, was poor.

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Systemic lupus erythematosus (SLE) is an autoimmune disorder that can manifest with a wide range of clinical features, including peripheral nervous system involvement. Among the neurological complications associated with SLE, chronic inflammatory demyelinating polyneuropathy (CIDP) is a rare but significant entity. This case report explores the complex relationship between CIDP and SLE, emphasizing the challenges in diagnosis and the complexities of treatment strategies. We present the case of a patient diagnosed with CIDP as the initial manifestation of SLE, who exhibited a remarkable response to a unique treatment approach. This case underscores the potential overlap of these two conditions, the need for individualized diagnostic, and the importance of considering lupus activity when making therapeutic decisions. While conventional treatment approaches for CIDP are established, the management of CIDP in the context of SLE requires a thorough approach. This report presents a case where early intervention with steroids and cyclophosphamide yielded favorable outcomes, providing insights into alternative treatment options. As this subset of patients remains underrepresented in clinical trials, further research is needed to establish clear guidelines for the management of CIDP in SLE, optimizing patient care while minimizing risks associated with immunomodulatory therapies.

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Inflammatory myositis (IM) presents a diagnostic challenge due to its multifaceted etiology and varying clinical presentations. This case involves a 55-year-old male with asymptomatic hypothyroidism, recent statin use, and rapidly progressing proximal muscle weakness. He presented with profound weakness in the upper and lower extremities, severely impairing his daily activities. The patient's medical history included recent hospitalizations for idiopathic interstitial lung disease, myopericarditis, and pneumonia, adding complexity to his condition. Laboratory findings revealed elevated serum muscle enzymes, notably creatine kinase, indicating muscle damage and rhabdomyolysis. Serological testing confirmed the absence of myositis-specific antibodies and anti-3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR) antibodies. The patient was eventually diagnosed with IM and rhabdomyolysis, likely secondary to statin use or hypothyroidism. Treatment with methylprednisolone, levothyroxine, and discontinuation of atorvastatin led to rapid improvements in AST levels and overall muscle strength. This case highlights the challenges of managing IM and emphasizes the importance of assessing thyroid function before initiating lipid-lowering therapy.

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Dermatomyositis (DM) is a rare inflammatory myopathy with an incidence of 9.63 per 1 000 000 people and typically presents with skin rash and muscle weakness. We report a case of DM that presented with proximal muscle weakness, normal creatine phosphokinase (CPK), negative myositis antibody panel, and non-specific histopathological findings on muscle biopsy, without initial skin involvement. A 67-year-old male presented with subacute bilateral proximal lower-extremity weakness and weight loss of 20 pounds over 3 months. Laboratory investigation was significant for elevated erythrocyte sedimentation rate, C-reactive protein, CPK, and aldolase, with negative myositis-specific antibodies. Femur magnetic resonance imaging revealed subcutaneous, fascial, and muscle edema throughout quadriceps and gluteal muscles. Muscle biopsy showed myofiber atrophy with perivascular and endomysial T-lymphocytes and histiocytes, as well as scattered necrotic myofibers. He was diagnosed with inflammatory myositis and started on prednisone and monthly IVIG infusions. At 2-month follow-up, he reported new rashes on the extensor surfaces of the hands consistent with Gottron's papules, mechanic's hands, and livedo reticularis of feet and arms. Cases of DM that present with myopathy and later develop skin changes are rare. Our patient had several months of progressive proximal muscle weakness, and skin changes occurred after he was started on treatment. Laboratory findings include elevated CPK, aldolase, and myositis-specific auto-antibodies. Muscle biopsy helps in diagnosis; however, findings may be nonspecific-as was the case in our patient. Corticosteroids are first-line treatment. Long-term follow-up studies are necessary to better understand the incidence of late-onset development of typical skin findings.

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Idiopathic inflammatory myopathies (IIMs) are a diverse group of diseases characterized by proximal muscle weakness and inflammation in skeletal muscle. Phenotypically, the subtypes include dermatomyositis, polymyositis, inclusion body myositis, and amyopathic dermatomyositis. The most common IIM in children is juvenile dermatomyositis (JDM). In contrast to adult dermatomyositis (DM), children are likely to have frequent relapses, vasculopathy, and long-term metabolic and other complications like lipodystrophy, insulin resistance, and calcinosis. Significant advances in our understanding of pathogenesis, disease course, and treatment of JDM has changed the therapeutic landscape and improved outcomes in children. Myositis-specific autoantibodies and myositis-associated autoantibodies have unique clinical associations, disease course and help predict response to therapy. A multidisciplinary approach including exercise programs and psychosocial support is essential. The first line of treatment is a combination of corticosteroids and methotrexate (MTX). Other targeted immunosuppressive therapy is used in refractory cases. Early recognition and timely referral to a specialist center remain pivotal to improving the mortality and morbidity associated with this disease.

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Anti-synthetase syndrome (ASS) is a rare autoimmune disease. Since the knowledge of ASS remains limited, we conducted the retrospective study aiming to describe clinical characteristics and identify variables associated with interstitial lung disease (ILD) and mortality among patients with ASS. Patients diagnosed with ASS from January 2013 to October 2022 were included. Patient demographics, clinical manifestations, myositis auto-antibody profiles, HRCT findings, and laboratory tests were collected. Variables associated with mortality risk and ILD were evaluated using the Cox proportional hazards model and the logistic regression model, respectively. A total of 82 patients with ASS were included. Clinical manifestations included arthritis (57%), Raynaud's phenomenon (32%), mechanic's hands (29%), fever (26%), and myositis (17%). The myositis auto-antibody profiles included anti-PL-7 (29%), anti-Jo-1 (27%), anti-EJ (17%), anti-PL-12 (16%), and anti-OJ (11%). ILD was observed in 64 patients (78%). Among patients with ILD, 21 initially presented with ILD before developing other ASS clinical manifestations, 29 simultaneously presented with ILD and other symptoms, and 14 had isolated ILD throughout follow-up. Overall, 6 patients presented with rapid-progressive ILD. With a median follow-up time of 2.5 years, mortality was observed in 10 patients (12.2%). Factors associated with mortality included increased lymphocyte counts (adjusted HR, 0.74; 95% CI, 0.61-0.91; p < 0.01), isolated ILD (adjusted HR, 9.59; 95% CI, 1.52-60.61; p = 0.02) and the presence of anti-Ro52 antibodies (adjusted HR, 0.14; 95% CI, 0.02-0.93; p = 0.04). Factors associated with ILD included age (adjusted OR, 1.10; 95% CI, 1.03-1.18; p = 0.01), presence of anti-Ro52 antibodies (adjusted OR, 17.92; 95% CI, 2.13-138.68; p = 0.01), and presence of arthritis (adjusted OR, 0.09; 95% CI, 0.01-0.75; p = 0.03). Our study demonstrated a favorable overall mortality rate among ASS patients.

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Scleromyositis is a new clinical entity, which not only has clinical and histopathological components of systemic sclerosis and inflammatory myopathy but is also characterized by presenting unique characteristics, which may not be in the previously mentioned diseases. Up until now, there are no specific classification criteria proposed by the American College of Rheumatology or the European League Against Rheumatism (ACR/EULAR). This paper presents a case report of a female patient in her 60s who was admitted to our institution due to muscle weakness in her legs and dysphagia. Within her diagnosis approach, clinical characteristics compatible with autoimmune myopathy were found; however, she presented with anti-PM/Scl75 antibody-positive results. In this paper, we emphasized the clinical characteristics and forms of presentation of scleromyositis, additionally discussing the available treatment for this entity.

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OBJECTIVES: Idiopathic inflammatory myopathies (IIMs) are heterogeneous diseases characterized by skeletal muscle inflammation associated with cutaneous, pulmonary, and/or other visceral organ involvement. Intravenous immunoglobulin (IVIG) has been recommended as an adjunct therapy for IIM patients refractory to conventional therapy. However, IVIG has high resource needs and increased risk of adverse reactions. Subcutaneous immunoglobulin (SCIG) therapy has been used as an alternative to IVIG in primary immunodeficiencies and neuroinflammatory disorders. We assessed the satisfaction, patient preference and effectiveness in IIM patients transitioned from IVIG to SCIG. METHODS: We retrospectively reviewed consecutive 20 patients with IIM who were transitioned from IVIG to SCIG therapy for >12 months. Patient preference between IVIG vs SCIG was surveyed using a questionnaire previously used in studies with neuroinflammatory conditions. In addition, disease flares, changes in immunosuppression, cumulative prednisone doses and global disease activity were evaluated using the Myositis Intention to Treat Index (MITAX) 12-months prior to- and post-SCIG initiation. RESULTS: Most patients (78.9%) preferred SCIG over IVIG and preferred home-based therapies to hospital-based therapies. There was no significant difference in global disease activity (MITAX 3.31 vs 3.02) nor in cumulative steroid doses 12-months prior to- or post-SCIG initiation. Three patients experienced disease flares, 5 escalated in immunosuppression, while 4 patients deescalated in immunosuppressive medications. CONCLUSIONS: SCIG is preferred by most patients over IVIG without a substantial increased disease activity or need for additional corticosteroids. Future cost effectiveness studies may provide an additional rationale for utilizing SCIG over IVIG for maintenance therapy for IIM.

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INTRODUCTION: Myositis-specific antibodies (MSA) play an important role in the clinical presentation and prognosis of patients with idiopathic inflammatory myositis (IIM). Anti-NXP-2 is one of the newly described MSA. OBJECTIVE: We aimed to describe various clinical presentations associated with anti-NXP2 antibodies and assess response to treatment. METHODS: In this retrospective study, the electronic medical records of all patients who tested positive for anti-NXP2 during June 2019 to April 2022 were screened. Details of demography, clinical presentation, and treatment data were recorded. The anti-NXP2 was tested using the Euro line test kit. Any patient who had an intensity of ≥1+ was considered testing positive. The diagnosis of IIM was reviewed after applying the 2017 European League of Rheumatology (EULAR)/American College of Rheumatology (ACR) criteria of myositis. RESULTS: Among the 660 suspected patients, 470 (71.2%) patients were positive for IIM, and 28 (5.95%) patients were positive for anti-NXP2. From anti-NXP2-antibody positive, 21/470 (4.46%) patients fulfilled criteria for IIM. Among 12 adult (57.14%) patients with IIM, 7 (58.33%) presented as polymyositis (PM) and 5 (41.6%) as dermatomyositis (DM) with median age at presentation of 45 (IQR: 25-58) years. Calcinosis and subcutaneous oedema were observed in 4 (19%) and 2 (9.52%), respectively; myalgia in 6 (28.6%); and distal muscle weakness in 5 (23.8%) patients. Malignancy at the time of diagnosis was observed in two adults with IIM (16.7%), one with DM (intraductal breast cancer), and another with PM (anaplastic large cell lymphoma). Remaining, 9 had juvenile dermatomyositis (JDM) with a median age of 4 (IQR: 3-8) years. Seven (77.8%) patients with JDM had skin rash specific for DM (heliotrope rash and Gottron's papule). None of the patients had cardiac and lung involvement, while GI symptoms, especially dysphagia, were present in 5 (23.8%) patients. During a median follow-up of 19 months (IQR: 12-26 months), 19/19 patients reported improvement and were in remission with treatment. CONCLUSION: The current study shows that adult DM patients with anti-NXP-2 autoantibodies have a unique clinical phenotype. Its presentation differs between adult and JDM, even in different parts of the world. Muscle weakness is mild and responds to treatment. Dysphagia needs more time and aggressive IS for improvement as compared to other muscle involvement. Key Points • Anti-NXP-2 antibody presentation varied from adult to child, as in different parts of the world. • In Indian adult patients, non-specific skin manifestations were more common, whereas in JDM, specific skin features were common. • There was less likely involvement of the lung and heart. But more risk of GI involvement requiring aggressive management. • Adult with anti-NXP-2 antibody should be screened for malignancy at the time of presentation.

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