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Objective 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. Methods 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. Results 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). Conclusion Muscle MRI holds promise in predicting muscle pathology, disease subtypes and clinical manifestations of IIMs. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Juvenile dermatomyositis is a systemic autoimmune disease characterized by progressive proximal muscle weakness, pathognomonic rashes, and often the presence of myositis-specific antibodies. Consensus treatment plans for pediatric patients with juvenile dermatomyositis recommend steroids and methotrexate as initial therapy. Patients with anti-transcription intermediary factor 1 gamma (anti-TIF-1γ) antibodies tend to have more refractory disease requiring more aggressive treatment with intravenous immunoglobulin, which is typically well tolerated. We describe two pediatric patients diagnosed with anti-TIF-1γ antibody-positive juvenile dermatomyositis who developed persistent increased intracranial pressure following intravenous immunoglobulin treatment. These cases suggest a potential association between treatment with intravenous immunoglobulin and increased intracranial pressure, a side effect that is not readily known. The shared anti-TIF-1γ positivity in both patients may suggest a possible concern for intracranial hypertension among juvenile dermatomyositis patients with this myositis-specific antibody.

Background Idiopathic inflammatory myopathy (IIM) is a group of connective tissue diseases characterized by muscle inflammation and muscle weakness, lung involvement is an important factor affecting the prognosis of patients. IIM can be classified into different clinical subtypes based on myositis-specific antibodies (MSAs), there are significant differences in clinical manifestations, organ involvement, prognosis and the risk of interstitial lung disease among different clinical subtypes. Objective To explore the characteristics of IIM and its different clinical subtypes, the risk factors for the development of interstitial lung disease. Methods The clinical data of patients hospitalizedin department of rheumatology and immunology of the First Affiliated Hospital of Kunming Medical University and diagnosed with IIM from April 2018 to February 2021 were collected. The included patients were divided into four clinical subtypes based on MSAs, including anti-MDA5-positive dermatomyositis (DM), anti-MDA5-negative DM, immune-mediated necrotizing myositis (IMNM) and anti-synthetase syndrome (ASS) subtypes. The general data, clinical manifestations, laboratory examination results were compared among different clinical subtypes. Multivariate Logistic regression model was established to explore the risk factors for ILD in patients with IIM. Results The 150 patients with IIM were divided into 4 clinical subtypes, including 30 patients with anti-MDA5-positive DM subtype (20.0%), 58 patients with anti-MDA5-negative DM subtype (38.7%), 14 patients with IMNM subtype (9.3%), and 48 patients with ASS subtype (32.0%). There were significant differences in the incidence of muscle weakness, myalgia, ILD, heliotrope rash, shawl sign, Gottron papules or Gottron sign, arthralgia, periungual red spot and dysphagia among the four clinical subtypes (P403.2 μg/L, IgG>14.15 g/L, LDH>359.5 U/L were all risk factors for ILD in IIM (P

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Abstract Background The coexistence of two myositis-specific autoantibodies (MSA) is considered extremely rare. We describe three patients with both anti-signal recognition particle (SRP) antibodies and another MSA in serum. Methods We performed a retrospective clinical data collection and follow-up studies of the clinical manifestations and treatment outcome of three patients positive with anti-SRP antibodies and other MSAs. IgG antibodies against MSAs were detected using commercial line immunoblot assay. Results The tests of MSA showed positive result of anti-SRP antibodies and another one MSA including anti-TIF1-γ, anti-Jo1, or anti-EJ antibodies, respectively. The proximal muscle weakness appeared in 2 patients; interstitial lung disease presented in 2 patients. The serum CK level was elevated in 1 patient. The muscle biopsy showed necrotizing myopathy in 1 patient and deposition of membrane attack complex on scattered myofibers in the other one patient. One of the two patients with interstitial lung disease died because of respiratory failure. One patient had completely improved and the other one showed partial remission after immunosuppressive therapy. Conclusions The patients with anti-SRP antibodies co-occurred with the other MSA may have various clinical characteristics. The clinicopathological phenotypes of these patients seem to be mainly caused by one of the MSAs, namely the responsible antibody.

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.

Background: The coexistence of two myositis-specific autoantibodies (MSA) is considered extremely rare. We describe three patients with both anti-signal recognition particle (SRP) antibodies and another MSA in serum. Methods: We performed a retrospective clinical data collection and follow-up studies of the clinical manifestations and treatment outcome of three patients positive with anti-SRP antibodies and other MSAs. IgG antibodies against MSAs were detected using commercial line immunoblot assay. Results: The tests of MSA showed positive result of anti-SRP antibodies and another one MSA including anti-TIF1-γ, anti-Jo1, or anti-EJ antibodies, respectively. The proximal muscle weakness appeared in 2 patients; interstitial lung disease presented in 2 patients. The serum CK level was elevated in 1 patient. The muscle biopsy showed necrotizing myopathy in 1 patient and deposition of membrane attack complex on scattered myofibers in the other one patient. One of the two patients with interstitial lung disease died because of respiratory failure. One patient had completely improved and the other one showed partial remission after immunosuppressive therapy. Conclusions: The patients with anti-SRP antibodies co-occurred with the other MSA may have various clinical characteristics. The clinicopathological phenotypes of these patients seem to be mainly caused by one of the MSAs, namely the responsible antibody. [ABSTRACT FROM AUTHOR]

Background: The usefulness of myositis-specific autoantibodies (MSAs) and myositis-associated autoantibodies (MAAs) for the assessment of idiopathic inflammatory myopathies (IIMs) is acknowledged, but laboratory standardization remains a challenge. We detected MSAs/MAAs by multi-analytic line immunoassay (LIA) and particle-based multi-analyte technology (PMAT) in a multicenter cohort of patients with IIMs. Methods: We tested the sera from 411 patients affected with definite IIM, including 142 polymyositis (PM), 147 dermatomyositis (DM), 19 cancer-associated myositis, and 103 overlap myositis syndrome (OM), and from 269 controls. MSAs/MAAs were determined by 16Ags LIA in all sera, and anti-HMGCR by ELISA in 157/411 IIM sera and 91/269 control sera. The analytical specificity of LIA/HMGCR ELISA was compared with that of PMAT in 89 MSA+ IIM sera. Results: MSAs/MAAs were positive in 307/411 (75%) IIM patients and 65/269 (24%) controls by LIA (Odds Ratio 9.26, 95% CI 6.43–13.13, p < 0.0001). The sensitivity/specificity of individual MSAs/MAAs were: 20%/100% (Jo-1), 3%/99.3% (PL-7), 4%/98.8% (PL-12), 1%/100% (EJ), 0.7%/100% (OJ), 9%/98% (SRP), 5.6%/99.6% (TIF1γ), 4.6%/99.6% (MDA5), 8%/96% (Mi-2), 1.5%/98% (NXP2), 1.7%/100% (SAE1), 4%/92% (Ku), 8.5%/99% (PM/Scl-100), 8%/96% (PM/Scl-75), and 25.5%/79% (Ro52). Anti-HMGCR was found in 8/157 (5%) IIM patients and 0/176 (0%) controls by ELISA (p = 0.007). Concordance between LIA/HMGCR ELISA and PMAT was found in 78/89 (88%) samples. Individual MSAs detected by LIA were associated with IIM subsets: Jo-1 with PM and OM, PL-12 with OM, Mi-2, TIF1γ, and MDA5 with DM, SRP with PM, and PM/Scl-75/100 with OM (p < 0.001 for all). Conclusions: Since MSAs are mostly mutually exclusive, multi-specific antibody profiling seems effective for a targeted clinical-serologic approach to the diagnosis of IIMs. [ABSTRACT FROM AUTHOR]

The aim of this study is to assess the relationship between myositis specific (MSA) and myositis associated (MAA) antibodies and diagnosis (including idiopathic inflammatory myopathies [IIM] and other systemic autoimmune diseases [SAID]), and to explore the impact of antibody signal intensity in diagnostic accuracy. We retrospectively reviewed all the serum samples obtained from patients tested for MSA/MAA by line immunoassay (LIA) between 01/01/2018 and 31/12/2020 in Ramón y Cajal University Hospital (Spain). Clinical true positive (CTP) MSAs and MAAs were defined as those patients with IIM or SAID with phenotypes expected of that MSA/MAA. Patients who did not have a phenotype compatible with that antibody were classified as clinical false positive (CFP). One hundred and thirty positive samples were analysed. Forty-six patients (33.38%) were classified as IIM, forty-two (32.3%) as SAID and forty-two (32.3%) as non-IIM/SAID. Among these 130 patients, 164 MSA/MAA were detected. Eighty-five (51.8%) positive MSA/MAA were classified as CTP, and seventy-nine (48.2%) as CFP. Strongly positive antibodies were more frequently CTP (35/47, 74.5%) than weak positives (54/68, 36.8%), (p ˂ 0.001). Antibodies classified as CTP had a higher signal intensity than CFP (36.77 AU vs 20.00 AU, CI95% 7.79–22.09, p ˂ 0.001). The probability of a CFP was associated to negative ANA, low ANA titer, and multiple positive MSA/MAA (p ˂ 0.001). In this study, we confirmed that CFP results using LIA are frequent, and are associated with low signal intensity MSA/MAA, negative ANA, lower titer ANA, and with multiple positive samples. [ABSTRACT FROM AUTHOR]

Dermatomyositis is a clinically heterogenous inflammatory myopathy with unique cutaneous features. Myositis-specific antibodies can aid in diagnosis and anticipation of patient prognosis. Herein, we report a 22-year-old man who presented with multifocal erythematous plaques with violaceous papules on his bilateral elbows, neck, and face. He was diagnosed with biopsy-proven dermatomyositis and determined to be seropositive for nuclear matrix protein 2 antibody (NXP-2). He was treated with systemic corticosteroids, then intravenous methylprednisolone and azathioprine, and ultimately achieved greatest treatment response with intravenous immune globulin therapy.

Dermatomyositis (DM) is a systemic autoimmune disease characterized by unique cutaneous manifestations and inflammatory myopathies. With the discovery of myositis-specific antibodies (MSAs), patients with DM, especially those with a higher risk of life-threatening complications, can be classified according to the MSA type. This retrospective study aimed to investigate the clinical significance of MSAs in patients with DM in Taiwan. A total of 33 patients with DM who underwent the MSA test, including 26 with classic DM and 7 with amyopathic DM, were included. There were 13 men and 20 women, with a mean age at diagnosis of 49.6 years. MSA was detected in 26 (78.8%) of 33 patients with DM. The most frequently detected MSA was anti-melanoma differentiation-associated protein 5 (MDA5) (10/33, 30.3%) followed by anti-transcription intermediary factor-1γ (TIF-1γ) (8/33, 24.2%). Dysphagia was present in 6 (18.2%) of the 33 patients and more frequently developed in patients with anti-TIF-1γ (+) (5/8, 62.5%) than those with anti-TIF-1γ (−) (1/25, 4.0%). Interstitial lung disease was noted in 15 patients (45.5%) and developed more frequently in patients with anti-MDA5 (+) (7/10, 70.0%) than those with anti-MDA5 (−) (8/23, 34.8%). Malignancies were detected in 4 (12.1%) patients, with one each of anti-Mi-2 (+), anti-TIF-1γ (+), anti-ARS (+), and MSA (−). Mortality occurred in 6 (18.2%) patients, of whom 4 were anti-MDA5 (+). Anti-MDA5 and anti-TIF-1γ were the two most commonly detected MSAs. The presence of specific MSAs is associated with a certain phenotype, and integrating MSAs while evaluating DM aids in accurate patient management.

Fibromyalgia (FM) is a common rheumatologic disorder characterised by widespread muscular pain. Myalgia is also a common clinical feature in Connective Tissue Disease (CTD), and FM should be studied for the concomitant presence of a CTD. The aim of this study is to evaluate the prevalence of Myositis-Specific and Myositis-Associated Antibodies (MSA/MAA) in a cohort of FM patients. We enrolled 233 consecutive FM patients (defined according to the 2016 criteria) that did not report clinical signs of autoimmune disorders and followed them for at least one year. The patients were tested for MSA/MAA with immunoblotting. FM patients were seropositive for Antinuclear Antibodies (ANA) in 24% of cases, for MSA in 9%, and for MAA in 6%. A specific diagnosis of CTD was made in 12 patients (5.2%), namely, 5 cases of primary Sjögren's Syndrome and 7 of Idiopathic Inflammatory Myopathy. Seropositive patients showed clinical features similar to those who were seronegative at baseline. A CTD diagnosis was associated with ANA positivity (p = 0.03, X2 4.9), the presence of a speckled pattern (p = 0.02, X2 5.3), positivity for MAA (p = 0.004, X2 8.1), and MSA (p = 0.003, X2 9.2). In conclusion, a non-negligible proportion of FM patients may be seropositive for MSA/MAA, and that seropositivity might suggest a diagnosis of CTD. [ABSTRACT FROM AUTHOR]

Dermatomyositis (DM) is a systemic autoimmune disease characterized by unique cutaneous manifestations and inflammatory myopathies. With the discovery of myositis-specific antibodies (MSAs), patients with DM, especially those with a higher risk of life-threatening complications, can be classified according to the MSA type. This retrospective study aimed to investigate the clinical significance of MSAs in patients with DM in Taiwan. A total of 33 patients with DM who underwent the MSA test, including 26 with classic DM and 7 with amyopathic DM, were included. There were 13 men and 20 women, with a mean age at diagnosis of 49.6 years. MSA was detected in 26 (78.8%) of 33 patients with DM. The most frequently detected MSA was anti-melanoma differentiation-associated protein 5 (MDA5) (10/33, 30.3%) followed by anti-transcription intermediary factor-1γ (TIF-1γ) (8/33, 24.2%). Dysphagia was present in 6 (18.2%) of the 33 patients and more frequently developed in patients with anti-TIF-1γ (+) (5/8, 62.5%) than those with anti-TIF-1γ (−) (1/25, 4.0%). Interstitial lung disease was noted in 15 patients (45.5%) and developed more frequently in patients with anti-MDA5 (+) (7/10, 70.0%) than those with anti-MDA5 (−) (8/23, 34.8%). Malignancies were detected in 4 (12.1%) patients, with one each of anti-Mi-2 (+), anti-TIF-1γ (+), anti-ARS (+), and MSA (−). Mortality occurred in 6 (18.2%) patients, of whom 4 were anti-MDA5 (+). Anti-MDA5 and anti-TIF-1γ were the two most commonly detected MSAs. The presence of specific MSAs is associated with a certain phenotype, and integrating MSAs while evaluating DM aids in accurate patient management. [ABSTRACT FROM AUTHOR]

Background: The usefulness of myositis-specific autoantibodies (MSAs) and myositis-associated autoantibodies (MAAs) for the assessment of idiopathic inflammatory myopathies (IIMs) is acknowledged, but laboratory standardization remains a challenge. We detected MSAs/MAAs by multi-analytic line immunoassay (LIA) and particle-based multi-analyte technology (PMAT) in a multicenter cohort of patients with IIMs. Methods: We tested the sera from 411 patients affected with definite IIM, including 142 polymyositis (PM), 147 dermatomyositis (DM), 19 cancer-associated myositis, and 103 overlap myositis syndrome (OM), and from 269 controls. MSAs/MAAs were determined by 16Ags LIA in all sera, and anti-HMGCR by ELISA in 157/411 IIM sera and 91/269 control sera. The analytical specificity of LIA/HMGCR ELISA was compared with that of PMAT in 89 MSA+ IIM sera. Results: MSAs/MAAs were positive in 307/411 (75%) IIM patients and 65/269 (24%) controls by LIA (Odds Ratio 9.26, 95% CI 6.43–13.13, p < 0.0001). The sensitivity/specificity of individual MSAs/MAAs were: 20%/100% (Jo-1), 3%/99.3% (PL-7), 4%/98.8% (PL-12), 1%/100% (EJ), 0.7%/100% (OJ), 9%/98% (SRP), 5.6%/99.6% (TIF1γ), 4.6%/99.6% (MDA5), 8%/96% (Mi-2), 1.5%/98% (NXP2), 1.7%/100% (SAE1), 4%/92% (Ku), 8.5%/99% (PM/Scl-100), 8%/96% (PM/Scl-75), and 25.5%/79% (Ro52). Anti-HMGCR was found in 8/157 (5%) IIM patients and 0/176 (0%) controls by ELISA (p = 0.007). Concordance between LIA/HMGCR ELISA and PMAT was found in 78/89 (88%) samples. Individual MSAs detected by LIA were associated with IIM subsets: Jo-1 with PM and OM, PL-12 with OM, Mi-2, TIF1γ, and MDA5 with DM, SRP with PM, and PM/Scl-75/100 with OM (p < 0.001 for all). Conclusions: Since MSAs are mostly mutually exclusive, multi-specific antibody profiling seems effective for a targeted clinical-serologic approach to the diagnosis of IIMs.

The clinical presentation of dermatomyositis (DM) is diverse, with varied phenotypes that may be correlated with specific autoantibodies. The anti-melanoma differentiation-associated gene 5 (MDA5) antibody in DM is associated with an amyopathic phenotype of DM, with several unusual cutaneous manifestation and increased risk for rapidly progressive interstitial lung disease. Initial presentation may be subtle, but early diagnosis is key to initiation of proper immunosuppressive therapy. In this report, we describe perinasal edema and erythema as a presenting complaint of anti-MDA5 DM in an otherwise healthy 40-year-old woman. The edema began shortly after heavy sun exposure and was followed by painful papules in her hands and arthritis within a few weeks. She was found to have high titer of anti-CCP and anti-MDA5, and thus was diagnosed with DM and rheumatoid arthritis overlap. A CT chest, abdomen, and pelvis showed patchy ground-glass and interstitial opacities in bilateral lower lobes consistent with mild interstitial lung disease without evidence of malignancy. Perinasal cutaneous findings and arthralgias improved with initiation of prednisone. To our knowledge, this is the first report of perinasal edema as a presenting symptom for DM and should raise suspicion for MDA-5 disease.

Abstract Background Many patients with polymyositis (PM) or dermatomyositis (DM) have circulating myositis-specific antibodies (MSAs). Interstitial lung disease (ILD) is a common manifestation of PM/DM, and it can even precede the onset of characteristic muscle or skin manifestations. Furthermore, there appear to be some patients with ILD and circulating MSAs who do not develop muscle or skin disease even after prolonged follow-up. We sought to determine whether ILD is equally or more common than myositis or dermatitis at the time of initial detection of MSAs. Methods We identified all patients found to have circulating MSAs at our institution over a 4-year period and assessed for the presence of lung, muscle, and skin disease at the time of initial detection of MSAs. Among those found to have ILD, we compared demographic and clinical features, chest CT scan findings, and outcomes between those with PM/DM-associated ILD and those with ILD but no muscle or skin disease. Results A total of 3078 patients were tested for MSAs, and of these 40 were positive. Nine different MSAs were detected, with anti-histidyl tRNA synthetase (anti-Jo-1) being the most common (35% of MSAs). Among patients with positive MSAs, 86% were found to have ILD, compared to 39% and 28% with muscle and skin involvement, respectively (p

Abstract Background Dermatomyositis with positive anti-melanoma differentiation-associated gene 5 (anti-MDA5) antibody has a distinct phenotype associated with small hand joint arthritis, mucocutaneous ulceration, palmar papules and less muscle involvement. It is also associated with increased risk of rapidly progressive interstitial lung disease (RP-ILD) and has a high mortality rate in adults. There is evidence that cases complicated with spontaneous pneumomediastinum (PNM) have an increase in mortality. While most of the evidence for this rare disease is derived from the adult literature, we report a case diagnosed in an adolescent complicated with both RP-ILD and PNM with a good outcome after aggressive immunosuppressive therapy. Our case also illustrates the potential challenges in diagnosis of this condition in the setting of non-specific clinical manifestations, the need for a high index of suspicion, and the importance of testing for myositis-specific antibodies (MSA) early to aid in diagnosis given the risk of rapid progression in these patients. Case presentation A 16-year-old Chinese female presented with fever and cough for 1 day, and finger swelling for 3 weeks. Physical examination revealed arthritis of fingers and wrists, ulcers and palmar papules over fingers, hyperpigmentation of interphalangeal joints, and rash over the neck. The diagnosis of dermatomyositis was made 1 month later with the onset of malar rash, Gottron’s papules, calcinosis and myalgia. The diagnosis was supported by the presence of anti-MDA5 antibody and evidence of inflammatory myopathy on magnetic resonance imaging. In retrospect, she already had interstitial lung disease at first presentation manifested as cough and opacity on chest radiograph, which was later confirmed with chest computed tomography. She was treated according to adult guidelines with steroid and calcineurin inhibitor. Her disease was resistant to initial therapy and was complicated by RP-ILD and spontaneous PNM. Intensive immunosuppressive therapy including cyclophosphamide and rituximab were required to induce remission. Conclusions Recognition of distinct clinical features of anti-MDA5 antibody-positive dermatomyositis and testing for MSA is crucial in patients with skin ulceration and abnormal pulmonary findings of unknown etiology, as prompt diagnosis with early aggressive treatment and anticipation of complications could make a difference in the outcome of this disease with high mortality.

Objectives Myositis-specific autoantibodies (MSAs) define distinct clinical subsets of idiopathic inflammatory myopathies (IIMs). The anti-nuclear matrix protein 2 (NXP2) antibody, a MSA detected in juvenile/adult IIMs, has been reported to be associated with a high risk of subcutaneous calcinosis, subcutaneous oedema and internal malignancies. The study aimed to clarify the clinical features of anti-NXP2 antibody-positive IIMs in detail. Methods This was a multicentre retrospective observational study on 76 anti-NXP2 antibody-positive patients. The antibody was detected via a serological assay using immunoprecipitation and western blotting. The patients were selected from 162 consecutive Japanese patients with IIMs. Results The cohort of anti-NXP2 antibody-positive IIMs included 29 juvenile patients and 47 adult patients. Twenty-seven (35.5%) patients presented with polymyositis phenotype without dermatomyositis-specific skin manifestations (heliotrope rash or Gottron sign/papules); this was more common in the adults than children (48.9% vs 15.8%, P  < 0.01). Nine (11.8%) patients had subcutaneous calcinosis, and 20 (26.3%) patients had subcutaneous oedema. In addition, the proportion of patients with muscle weakness extending to the distal limbs was high (36 patients [47.4%]) in this cohort. Adult patients had a higher prevalence of malignancy than the general population (age-standardized incidence ratio of malignancies: 22.4). Conclusion Anti-NXP2 antibody-positive IIMs, which include dermatomyositis sine dermatitis, are characterized by atypical skin manifestations and extensive muscular involvement. [ABSTRACT FROM AUTHOR]

The clinical presentation of dermatomyositis (DM) is diverse, with varied phenotypes that may be correlated with specific autoantibodies. The anti-melanoma differentiation-associated gene 5 (MDA5) antibody in DM is associated with an amyopathic phenotype of DM, with several unusual cutaneous manifestation and increased risk for rapidly progressive interstitial lung disease. Initial presentation may be subtle, but early diagnosis is key to initiation of proper immunosuppressive therapy. In this report, we describe perinasal edema and erythema as a presenting complaint of anti-MDA5 DM in an otherwise healthy 40-year-old woman. The edema began shortly after heavy sun exposure and was followed by painful papules in her hands and arthritis within a few weeks. She was found to have high titer of anti-CCP and anti-MDA5, and thus was diagnosed with DM and rheumatoid arthritis overlap. A CT chest, abdomen, and pelvis showed patchy ground-glass and interstitial opacities in bilateral lower lobes consistent with mild interstitial lung disease without evidence of malignancy. Perinasal cutaneous findings and arthralgias improved with initiation of prednisone. To our knowledge, this is the first report of perinasal edema as a presenting symptom for DM and should raise suspicion for MDA-5 disease. [ABSTRACT FROM AUTHOR]

Objective: To study autoantibody profile in juvenile dermatomyositis (JDM) and to look for phenotypic associations of these autoantibodies, if any. Methods: Thirty-four children with JDM with a minimum follow-up duration of 24 mo were enrolled. Clinical findings and investigations at the time of diagnosis were noted from the clinic records. At inclusion, they were clinically evaluated for residual disease, disease activity and complications. All the enrolled patients were tested for antinuclear antibodies (ANA), muscle specific antibodies (MSA) and myositis associated autoantibodies (MAA). Results: ANA positivity was seen in 14/34 children. At least one MSA or MAA was present in 8/34 children. Anti-SRP, anti-MDA-5, and anti-Mi-2 antibodies were present in 4, 3, and 1 patient, respectively. Anti-SSA/Ro52 antibody was positive in 1 child. All four children with anti-SRP antibody were girls, who had polycyclic course. Two of them developed calcinosis. Prominent skin involvement with less severe muscle involvement and monocyclic course were seen in patients with anti-MDA-5 antibody. Two of them had arthritis/arthralgia at initial presentation. The only patient with anti-Mi-2 had normal muscle strength at enrollment. None of the patients had anti-synthetase antibodies (anti-Jo-1, anti-PL-7, anti-PL-12, anti-EJ), anti-Ku, anti-Scl-70, anti-NXP-2 or anti-HMG CoA. Conclusion: Eight patients tested positive for at least one MSA or MAA. The prevalence of autoantibodies was low. Positivity for anti-SRP, anti-MDA-5, anti-Mi-2 and anti-SSA/Ro52 antibodies was seen in 4, 3, 1 and 1 patients, respectively. Ethnic differences and testing for autoantibodies during/after therapy could be responsible for the low positivity rate for autoantibodies. [ABSTRACT FROM AUTHOR]

Background. In recent years, many novel myositis-specific autoantibodies (MSAs) have been identified. However, their links with the pathogenesis and clinical manifestations of inflammatory myopathies remain uncertain. Objectives. To characterize the population of adult dermatomyositis (DM) and polymyositis (PM) patients treated at our center for autoimmune diseases using clinical and laboratory measures. Materials and methods. According to the Bohan and Peter criteria, we retrospectively analyzed patients who fulfilled diagnostic criteria for DM or PM. Myositis-specific autoantibodies and myositis-associated autoantibodies (MAAs) were identified using immunoblot assays. Results. Fifty-one PM (71% women) and 36 DM (67% women) Caucasian patients with a median age of 58 (range: 21-88) years who met the definite or probable diagnostic criteria for myositis were included in the study. Myositis-specific autoantibodies were identified in 63 (72%) patients, whereas MAAs were observed in 43 (49%) of them. Interstitial lung disease (ILD) was characteristic of PM patients (67%, χ² with Yates's correction (χc²) = 13.8078, df = 1, p = 0.0002), being associated with anti-Jo-1 or anti-PL-12 antibodies (fraction comparison test (FCT) 6.4878, p < 0.0001, 6.8354, p = 0.0003, respectively). Interestingly, among patients with anti-MDA5 antibodies (n = 8, 9.2%), all but one had an amyopathic form, with more frequent ILD, skin changes and arthralgias than observed in other patients (FCT 4.7029, p = 0.0228 and p = 7.7986, p = 0.0357, p = 4.7029 and p = 0.0228, respectively). Anti-signal recognition particle (SRP) was strongly associated with the Raynaud's phenomenon (FCT 4.1144, p = 0.0289) and the highest muscle injury markers (Mann--Whitney U test, z = 2.5293, p = 0.0114). Malignancy was recorded in 14 (16%) patients and was equally common in those with PM and DM. The anti-TIF-1γ was the most frequently related to cancer χ² = 14.7691, df = 1, p < 0.0001). The anti-Mi-2α, similarly prevalent in DM and PM, was typically accompanied by skin changes (FCT 7.7986, p = 0.0357) but not ILD (FCT 8.7339, p = 0.0026). Conclusions. Identification of MSAs might help to predict the clinical course of the autoimmune myopathy and malignancy risk. However, these antibodies were absent in about 30% of patients with typical PM or DM manifestations, which encourages further research in this area. [ABSTRACT FROM AUTHOR]

Anti-melanoma differentiation-associated gene 5 (MDA5) and anti-aminoacyl-tRNA synthetase (ARS) antibodies are two major myositis-specific autoantibodies with distinct clinical features. However, the clinical course remains unclear in patients with clinically amyopathic dermatomyositis (CADM)-interstitial lung disease (ILD) who have co-existing anti-MDA5 and anti-ARS antibodies. Here, we describe the case of a 32-year-old woman with CADM-ILD who had anti-MDA5 and anti-PL12 antibodies. Her serum ferritin level was within the normal range. However, chest computed tomography revealed bilateral lower-lobe consolidation and ground-glass opacities. Treatment with prednisolone and immunosuppressants was successful in improving the skin lesion and ILD, but relapse occurred on reducing the dose of prednisolone. These clinical features match those of anti-ARS antibody-positive dermatomyositis-ILD. Because these two conditions show significantly different clinical features and require different intensities of treatment, clinicians should carefully follow-up these patients throughout the course of the disease.

Fibromyalgia (FM) is a common rheumatologic disorder characterised by widespread muscular pain. Myalgia is also a common clinical feature in Connective Tissue Disease (CTD), and FM should be studied for the concomitant presence of a CTD. The aim of this study is to evaluate the prevalence of Myositis-Specific and Myositis-Associated Antibodies (MSA/MAA) in a cohort of FM patients. We enrolled 233 consecutive FM patients (defined according to the 2016 criteria) that did not report clinical signs of autoimmune disorders and followed them for at least one year. The patients were tested for MSA/MAA with immunoblotting. FM patients were seropositive for Antinuclear Antibodies (ANA) in 24% of cases, for MSA in 9%, and for MAA in 6%. A specific diagnosis of CTD was made in 12 patients (5.2%), namely, 5 cases of primary Sjögren’s Syndrome and 7 of Idiopathic Inflammatory Myopathy. Seropositive patients showed clinical features similar to those who were seronegative at baseline. A CTD diagnosis was associated with ANA positivity (p = 0.03, X2 4.9), the presence of a speckled pattern (p = 0.02, X2 5.3), positivity for MAA (p = 0.004, X2 8.1), and MSA (p = 0.003, X2 9.2). In conclusion, a non-negligible proportion of FM patients may be seropositive for MSA/MAA, and that seropositivity might suggest a diagnosis of CTD.

Competing Interests: Conflicts of interest Dr Min is on the advisory boards of Horizon and BMS, and is an investigator for Amgen, BI, BMS, and Priovant. The authors Arora, Kincaid, Sharma, and Mesinkovska have no conflicts of interest to declare.

Background: Many patients with polymyositis (PM) or dermatomyositis (DM) have circulating myositis-specific antibodies (MSAs). Interstitial lung disease (ILD) is a common manifestation of PM/DM, and it can even precede the onset of characteristic muscle or skin manifestations. Furthermore, there appear to be some patients with ILD and circulating MSAs who do not develop muscle or skin disease even after prolonged follow-up. We sought to determine whether ILD is equally or more common than myositis or dermatitis at the time of initial detection of MSAs.Methods: We identified all patients found to have circulating MSAs at our institution over a 4-year period and assessed for the presence of lung, muscle, and skin disease at the time of initial detection of MSAs. Among those found to have ILD, we compared demographic and clinical features, chest CT scan findings, and outcomes between those with PM/DM-associated ILD and those with ILD but no muscle or skin disease.Results: A total of 3078 patients were tested for MSAs, and of these 40 were positive. Nine different MSAs were detected, with anti-histidyl tRNA synthetase (anti-Jo-1) being the most common (35% of MSAs). Among patients with positive MSAs, 86% were found to have ILD, compared to 39% and 28% with muscle and skin involvement, respectively (p < 0.001). Fifty percent of all MSA-positive patients had isolated ILD, with no evidence of muscle or skin disease. Those with isolated ILD were more likely to be older and have fibrotic changes on chest CT, less likely to receive immunomodulatory therapy, and had worse overall survival.Conclusions: In this study we found that individuals with circulating MSAs were more likely to have ILD than classic muscle or skin manifestations of PM/DM at the time of initial detection of MSAs. Our findings suggest that the presence of ILD should be considered a disease-defining manifestation in the presence of MSAs and incorporated into classification criteria for PM/DM. [ABSTRACT FROM AUTHOR]

Introduction/objectives: To describe clinical features in patients with inflammatory myopathies (IMs) from the Argentine Registry of Inflammatory Myopathies, and their relationship with myositis-specific antibodies (MSAs). Methods: This cross-sectional study included 360 adult patients with dermatomyositis (DM), polymyositis (PM), and inclusion body myositis. Demographics, clinical, and serological characteristics were retrospectively recorded (2016–2019). MSAs were determined by immunoblotting. Patients who were positive for anti-Jo-1, Mi-2, and MDA5 were compared against a group of patients, taken as reference group, who were negative for all MSAs. Results: Women 72%, median age at diagnosis was 47.3 years (18–82). The most frequent subtypes were DM (43.9%) followed by PM (30%).The most frequent MSAs were anti-Jo-1 (51/317), 16.1%; MDA5 (12/111), 10.8%, and Mi-2 (23/226), 10.2%. Anti-Jo-1 was associated (p < 0.05) with a higher frequency of chronic disease course, interstitial lung disease (ILD), arthritis, and mechanic's hands. Anti-Mi-2 was found in patients who had higher frequency of skin manifestations and higher CK values (p < 0.001). Patients with anti-MDA5 had normal or low CK levels. Anti-MDA5 was associated (p < 0.05) with skin manifestations, arthritis, and ILD. The rest of MSAs had frequencies lower than 8%. Anti-TIF1ϒ was found in eight DM patients and one had cancer. Anti-SRP was found in seven patients who had PM and elevated CK. Conclusion: Anti-Jo-1 was the most frequent MSA, and was associated with ILD; MDA5 was associated with CADM and ILD, and Mi-2, with classical DM. Despite the different prevalence with respect to other cohorts, the clinical characteristics for each MSA group were similar to the data reported in other studies. Key Points • This study describes the prevalence of MSAs in the Argentine Registry of IMs. • Anti-Jo-1 and anti-MDA5 were associated with ILD. • Anti-Mi-2 was the third most frequent MSA, associated with classical DM. [ABSTRACT FROM AUTHOR]

Background: Dermatomyositis with positive anti-melanoma differentiation-associated gene 5 (anti-MDA5) antibody has a distinct phenotype associated with small hand joint arthritis, mucocutaneous ulceration, palmar papules and less muscle involvement. It is also associated with increased risk of rapidly progressive interstitial lung disease (RP-ILD) and has a high mortality rate in adults. There is evidence that cases complicated with spontaneous pneumomediastinum (PNM) have an increase in mortality. While most of the evidence for this rare disease is derived from the adult literature, we report a case diagnosed in an adolescent complicated with both RP-ILD and PNM with a good outcome after aggressive immunosuppressive therapy. Our case also illustrates the potential challenges in diagnosis of this condition in the setting of non-specific clinical manifestations, the need for a high index of suspicion, and the importance of testing for myositis-specific antibodies (MSA) early to aid in diagnosis given the risk of rapid progression in these patients. Case presentation: A 16-year-old Chinese female presented with fever and cough for 1 day, and finger swelling for 3 weeks. Physical examination revealed arthritis of fingers and wrists, ulcers and palmar papules over fingers, hyperpigmentation of interphalangeal joints, and rash over the neck. The diagnosis of dermatomyositis was made 1 month later with the onset of malar rash, Gottron's papules, calcinosis and myalgia. The diagnosis was supported by the presence of anti-MDA5 antibody and evidence of inflammatory myopathy on magnetic resonance imaging. In retrospect, she already had interstitial lung disease at first presentation manifested as cough and opacity on chest radiograph, which was later confirmed with chest computed tomography. She was treated according to adult guidelines with steroid and calcineurin inhibitor. Her disease was resistant to initial therapy and was complicated by RP-ILD and spontaneous PNM. Intensive immunosuppressive therapy including cyclophosphamide and rituximab were required to induce remission. Conclusions: Recognition of distinct clinical features of anti-MDA5 antibody-positive dermatomyositis and testing for MSA is crucial in patients with skin ulceration and abnormal pulmonary findings of unknown etiology, as prompt diagnosis with early aggressive treatment and anticipation of complications could make a difference in the outcome of this disease with high mortality. [ABSTRACT FROM AUTHOR]

Les myopathies inflammatoires idiopathiques, ou MII, sont un groupe de maladies acquises touchant le muscle à divers degrés de gravité, pouvant également atteindre d'autres organes. Elles regroupent les dermatomyosites, associant une atteinte musculaire fluctuante et cutanée typique ; les myosites à inclusions, à expression purement musculaire se traduisant par un déficit d'évolution lente ; et l'ancien groupe des « polymyosites », terme impropre qui regroupe en fait d'autre catégories de maladies, comme les myopathies nécrosantes auto-immunes, avec une atteinte musculaire souvent sévère au premier plan ; le syndrome des antisynthétases, qui associe une atteinte musculaire à une atteinte articulaire, ainsi que pulmonaire pouvant mettre en jeu le pronostic vital ; et les myosites de chevauchement, qui associent une atteinte musculaire à des atteintes d'organe de différentes connectivites. Le diagnostic d'une MII se base sur un examen clinique et un interrogatoire rigoureux, des données électromyographiques et un bilan immunologique avec recherche d'anticorps spécifique des myosites. Cette recherche d'anticorps doit parfois être étendue ou répétée pour arriver à classer correctement la maladie musculaire étudiée, les tests disponibles souffrant parfois de performances insuffisantes. La biopsie musculaire, bien que très informative, n'est plus systématiquement recommandée chez les patients ayant une clinique et des anticorps typiques. Certaines formes de MII restent cependant parfois difficiles à classer, la biopsie musculaire joue alors un rôle crucial pour poser un diagnostic étiologique précis. Idiopathic inflammatory myopathies, or IIM, are a group of acquired diseases that affect the muscle to a certain extent, and may also affect other organs. They include dermatomyositis, which can affect the muscle eventualy, with a typical skin rash; inclusion body myositis, with a purely muscular expression resulting in a slow progressive deficit; and the former group of "polymyositis", a misnomer that actually includes other categories of IIM, such as immune-mediated necrotizing myopathies, with a severe muscle involvement often presents from the onset of the disease; antisynthetase syndrome, which combines muscle damage, joint involvement and a potentially life-threatening lung disease; and overlapping myositis, which combines muscle damage with other organs involvement connected to another autoimmune disease. The diagnosis of IIM is based on rigorous clinical examination and interrogation, electromyographic data and immunological testing for myositis specific antibodies. This antibody dosage must be extended or repeated if necessary to classify correctly the muscle disease under investigation, as the available tests may not perform well enough. Muscle biopsy, although very informative, is not anymore systematically recommended when the clinic and the antibodies are typical. However, some forms of IIM are sometimes difficult to classify; in these cases, muscle biopsy plays a crucial role in the precise etiological diagnosis. [ABSTRACT FROM AUTHOR]

The term clinically amyopathic dermatomyositis (CADM) is used to represent a subgroup of patients with the typical cutaneous features of dermatomyositis (DM) in the absence of muscle involvement. Similar to classic DM, CADM can be associated with other connective tissue disorders and systemic manifestations such as interstitial lung disease and malignancy. Owing to the frequent discordance between muscle response and skin disease, the therapeutic approach to CADM represents a challenge. The current literature suggests that CADM treatment should follow a specific protocol, influenced by visceral involvement and the expression of certain myositis‐specific antibodies, and different from the recommendation in the presence of myositis. Here, we present five new cases of CADM. We describe the available therapeutic options for skin manifestations in this type of DM, and we propose a step‐by‐step therapeutic scheme, using the cutaneous dermatomyositis disease area and severity index to assess response. Our literature review establishes mycophenolate mofetil and intravenous immunoglobulin as the most frequently successful therapies in refractory skin disease. [ABSTRACT FROM AUTHOR]

In this study, we aimed at evaluating the contribution of an extended myositis-related antibodies (Abs) determination by immunoblot to the diagnosis, classification, and prognosis of idiopathic inflammatory myositis (IIM). Medical records of all the patients (n = 237) with myositis-related Ab requests addressed to our department over a one-year period were retrospectively analyzed. Patients were classified as IIM, auto-immune disease (AID) other than IIM, and other diagnosis, and examined for their Ab profiles as determined by immunoblot. Ab positivity was qualified semi-quantitatively as low or strong according to the manufacturer’s recommendations. Among the 45 Ab-positive patients, 49% were diagnosed an IIM, 22% another AID, and 29% another diagnosis. The clinico-serological patterns of the myositis-related Ab+ patients fully recapitulated those described in the literature. Among non-IIM patients, anti-PM-Scl was the most frequently detected Ab (38%), followed by anti-Mi-2 (15%), and anti-OJ (12%). Importantly, strong Ab positivity was significantly more detected in IIM vs. non-IIM patients (82% vs. 35%; p = .002). This difference was further increased when comparing MSAs only (95% vs. 36%; p = .0004). Accordingly, strong Ab positivity associated with high specificity (96%) and positive likelihood ratio (pLR =12) for IIM. Our data suggest that while myositis-related Ab, including MSA, can be detected by immunoblot in non-IIM patients, strong positivity is nevertheless highly predictive of IIM. In conclusion, this work suggests that relevant clinical contribution to IIM is provided by the immunoblot determination of myositis-related Ab, more especially when considering strong positive detection of MSA.

Dermatomyositis (DM) is an idiopathic inflammatory myopathy that is clinically heterogeneous and that can be difficult to diagnose. Cutaneous manifestations sometimes vary and may or may not parallel myositis and systemic involvement in time course or severity. Recent developments in our understanding of myositis-specific antibodies have the potential to change the diagnostic landscape of DM for dermatologists. Although phenotypic overlap exists, anti-Mi2, -MDA5, -NXP2, -TIF1, and -SAE antibodies may be correlated with distinct DM subtypes in terms of cutaneous manifestations, systemic involvement, and malignancy risk. This review highlights new findings on the DM-specific myositis-specific antibodies and their clinical associations in both adults and children. [ABSTRACT FROM AUTHOR]

Dermatomyositis (DM) is a rare 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 a multifactorial disease influenced by genetic, environmental and immunological factors. The immune response is characterized by activation of innate and adaptive immune mechanisms and a strong activation of the type I 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., (© 2023. The Author(s), under exclusive licence to Springer Medizin Verlag GmbH, ein Teil von Springer Nature.)

Background: Several viruses have been described as causes of acquired inflammatory myopathies; however, the mechanisms by which they cause muscle disease are still unclear. The aim of this study was to describe the laboratory features of benign acute myositis in a small case series.Methods: A detailed pathological and serological analysis was performed in five African migrants who developed an acute viral myositis complicated by rhabdomyolysis.Results: Muscle biopsies clearly documented an inflammatory myopathy with histological features similar to polymyositis including CD8+ T cells surrounding and invading nonnecrotic muscle fibers, CD68+ macrophages and major histocompatibility complex class I antigen upregulation. In addition, positivity for myositis-specific antibodies (MSA), in particular anti-aminoacyl tRNA synthetases, was found in the serum of two patients.Conclusions: Our study demonstrated that T-cell mediated injury occurs in muscle of patients with acute viral myositis, and that MSA may be present in the serum of these patients. [ABSTRACT FROM AUTHOR]

Although included in the serological domain of the ‘interstitial pneumonia with auto-immune features’ (IPAF) research statement, the search for myositis-specific antibodies (MSA) is not incorporated in routine clinical practice. The objective of the study was to evaluate MSA prevalence in an idiopathic interstitial pneumonia (IIP) cohort (n = 68) with suggestive morphological interstitial lung disease patterns. Twelve of 68 patients (17.6%) carried MSA, whereof only two were anti-nuclear antibody-positive. Besides female gender, no demographic or pulmonary function parameter was predictive for MSA positivity. MSA were present in 32.4% of IPAF patients (n = 37), being essential for IPAF diagnosis in four of them (10.8%). [ABSTRACT FROM AUTHOR]

In this study, we aimed at evaluating the contribution of an extended myositis-related antibodies (Abs) determination by immunoblot to the diagnosis, classification, and prognosis of idiopathic inflammatory myositis (IIM). Medical records of all the patients (n = 237) with myositis-related Ab requests addressed to our department over a one-year period were retrospectively analyzed. Patients were classified as IIM, auto-immune disease (AID) other than IIM, and other diagnosis, and examined for their Ab profiles as determined by immunoblot. Ab positivity was qualified semi-quantitatively as low or strong according to the manufacturer’s recommendations. Among the 45 Ab-positive patients, 49% were diagnosed an IIM, 22% another AID, and 29% another diagnosis. The clinico-serological patterns of the myositis-related Ab+ patients fully recapitulated those described in the literature. Among non-IIM patients, anti-PM-Scl was the most frequently detected Ab (38%), followed by anti-Mi-2 (15%), and anti-OJ (12%). Importantly, strong Ab positivity was significantly more detected in IIM vs. non-IIM patients (82% vs. 35%; p = .002). This difference was further increased when comparing MSAs only (95% vs. 36%; p = .0004). Accordingly, strong Ab positivity associated with high specificity (96%) and positive likelihood ratio (pLR =12) for IIM. Our data suggest that while myositis-related Ab, including MSA, can be detected by immunoblot in non-IIM patients, strong positivity is nevertheless highly predictive of IIM. In conclusion, this work suggests that relevant clinical contribution to IIM is provided by the immunoblot determination of myositis-related Ab, more especially when considering strong positive detection of MSA. [ABSTRACT FROM AUTHOR]

Autoantibodies are important in the diagnosis of dermatomyositis. They can be divided in two different groups: myositis-associated autoantibodies (MAA) prevailing in overlap syndromes, and myositis-specific autoantibodies (MSA), with diagnostic specificity exceeding 90%. Our purpose was to detect retrospectively the prevalence of the most common MSAs in a group of 19 adult DM patients (13 women, 6 men). A severe DM (SDM), with extensive cutaneous and muscular manifestations, dysphagia, and sometimes pneumopathy, was detected in ten cases. Three patients had a mild DM (MDM), with little muscle and skin impairment, and a short course. Four patients suffered from amyopathic DM (ADM), two from paraneoplastic DM (PDM). Each serum was tested for ANA, ENA, MAAs, MSAs. Myositis-specific autoantibodies were detected in 15 cases. The most frequent was anti-TIF1γ, associated with SDM or PDM in four out of seven cases. Anti-MDA5 antibodies were recorded in a SDM and in a ADM with lung fibrosis. Anti-Mi2 and anti-SRP antibodies were both detected in a MDM and in a SDM, whereas anti-SAE1 in a amyopathic form. Other antibodies (anti-NXP2, -Jo1, -PL7, -PL12, -OJ) were found in single patients with SDM. Our series confirmed that specific autoantibodies could be helpful to classify different clinical subsets, particularly in the case of paraneoplastic forms or association with pneumopathy. Moreover, they can help in predicting the disease evolution and influence therapeutic strategies. A greater number of cases should be useful to highlight the clinical and pathogenic role of these antibodies, and develop a homogeneous protocol for diagnosis and treatment. [ABSTRACT FROM AUTHOR]

The idiopathic inflammatory myopathies (IIMs) are a heterogeneous group of autoimmune diseases (collectively known as myositis) affecting the skeletal muscles as well as other organ systems such as skin, lungs, and joints. The primary forms of myositis include polymyositis (PM), dermatomyositis (PM), and immune-mediated necrotizing myopathy (IMNM). Patients with these diseases experience progressive proximal muscle weakness, have characteristic muscle biopsy findings, and produce autoantibodies that are associated with unique clinical features. One distinguishing feature of these patients is that they are also known to have an increased risk of cancer. Since the first description of the association in 1916, it has been extensively reported in the medical literature. However, there have been significant variations between the different studies with regard to the degree of cancer risk in patients with IIM. These discrepancies can, in part, be attributed to differences in the definition of malignancy-associated myositis used in different studies. In recent years, significant advances have been made in defining specific features of IIM that are associated with the development of malignancy. One of these has been myositis-specific antibodies (MSAs), which are linked to distinct clinical phenotypes and categorize patients into groups with more homogeneous features. Indeed, patients with certain MSAs seem to be at particularly increased risk of malignancy. This review attempts a systematic evaluation of research regarding the association between malignancy and myositis. [ABSTRACT FROM AUTHOR]

The article discusses the clinical and diagnostic value of autoantibodies in idiopathic inflammatory myositis (IIM). Topics discussed include major autoantibody subsets of myositis-specific autoantibodies (MSAs), the most common myositis-associated autoantibodies (MAAs), and the usefulness of MSAs and MAAs as diagnostic markers.