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Anti-3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR) myopathy is one of the subtypes of immune-mediated necrotizing myopathy. Anti-HMGCR antibodies induce complement activation,subsequently resulting in myofiber necrosis,regeneration with autophagy abnormalities and mitochondrial changes. The age of onset is from children to adulthood. Some patients have a history of exposure to statins. Most patients are subacute onset. The patients with chronic progressive process, are more like muscular dystrophy. The main symptoms are proximal symmetrical weakness of limbs and usually accompanied with extra-muscle symptoms. The MRI showed muscle edema in all patients and fatty infiltrates in some patients. Myositis-specific auto-antibodies and muscle biopsies play key roles in diagnosis of HMGCR myopathy. Corticosteroids and immunosuppressants were first line therapy. Pediatric patients or patients with chronic course are usually refractory, and the efficacy of different combinations of immunosuppressants needs to be further investigated.
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ABSTRACT Idiopathic inflammatory myopathies (IIM) are a heterogenous group of treatable myopathies. Patients present mainly to the rheumatologist and neurologists, complaining of acute or subacute onset of proximal weakness. Extramuscular manifestations may occur, including involvement of the lungs, skin, and joints. Classically, the diagnosis used to be made based on the creatine kinase level increase, abnormalities in electroneuromyography and presence of inflammatory infiltrates in the muscle biopsy. Recently, the importance of autoantibodies has increased, and now they may be identified in more than half of IIM patients. The continuous clinicoseropathological improvement in IIM knowledge has changed the way we see these patients and how we classify them. In the past, only polymyositis, dermatomyositis and inclusion body myopathy were described. Currently, immune-mediated necrotizing myopathy, overlap myositis and antisynthetase syndrome have been considered the most common forms of IIM in clinical practice, increasing the spectrum of classification. Patients previously considered to have polymyositis, in fact have these other forms of seropositive IIM. In this article, we reviewed the new concepts of classification, a practical way to make the diagnosis and how to plan the treatment of patients suffering from IIM.
RESUMO As miopatias inflamatórias idiopáticas (MII) são um grupo heterogêneo de miopatias tratáveis. Os pacientes procuram principalmente o reumatologista e o neurologista, queixando-se de início agudo ou subagudo de fraqueza proximal. Manifestações extramusculares podem ocorrer, incluindo envolvimento dos pulmões, pele e articulações. Classicamente, o diagnóstico era feito com base na elevação dos níveis de creatina quinase, anormalidades na eletroneuromiografia e presença de infiltrados inflamatórios na biópsia muscular. Recentemente, a importância dos autoanticorpos aumentou, e agora eles podem ser identificados em mais da metade dos pacientes com MII. A contínua melhora clínico-soropatológica no conhecimento do MII mudou a forma como vemos esses pacientes e como os classificamos. No passado, apenas polimiosite, dermatomiosite e miopatia por corpos de inclusão eram descritas. Atualmente, a miopatia necrosante imunomediada, a miosite de sobreposição e a síndrome antissintetase têm sido consideradas as formas mais comuns de MII na prática clínica, aumentando o espectro de classificação. Pacientes previamente considerados como portadores de polimiosite, na verdade, têm uma dessas outras formas de MII soropositivas. Neste artigo, revisamos os novos conceitos de classificação, uma forma prática de fazer o diagnóstico e como planejar o tratamento de pacientes que sofrem de MII.
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Objective:To explore clinical characteristics and treatment of pediatric anti-3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR) antibody-positive myopathy.Methods:Two cases of pediatric anti-HMGCR antibody-positive myopathy admitted to the Department of Neurology, Shenzhen Children′s Hospital from January to July 2020 were retrospectively analyzed for their clinical manifestations, creatine kinase (CK), myositis autoantibody, electromyography (EMG), muscle pathology, muscle magnetic resonance imaging (MRI), and treatment information.Results:Both of them were female cases.Case 1 was 3 years and 11 months old and case 2 was 7 years and 9 months old.They used to be healthy without history of statin use.Case 1 showed chronic onset of the disease, and case 2 had a subacute onset.The main clinical manifestations were progressive symmetric proximal muscle weakness accompanied by myalgia.Case 1 developed skin rash but case 2 did not.Significantly increased CK level was detected in both of them, which increased by 27.3-48.0 and 66.7-77.4 times of the upper limit before treatment in case 1 and case 2, respectively.They were diagnosed as muscular dystrophy at the early stage.EMG results suggested myogenic injuries in 2 cases, and muscle MRI showed extensive muscle edema.The muscle pathology of the 2 cases suggested muscle necrosis with a small amount of inflammatory cell infiltration.After diagnosis, both of them were treated with Methylprednisolone combined with intravenous immunoglobulin.CK decreased significantly but remained high, and muscle weakness was improved but did not return to normal.Oral Prednisone was given after discharge and case 2 was additionally medicated with azathioprine.Conclusions:Compared with adult patients, the clinical characteristics of pediatric anti-HMGCR antibody-positive myopathy are mostly similar.However, children patients usually have no history of statins and are more difficult to treat, less effective and worse prognosis.In addition, children patients are more likely to be diagnosed with " muscular dystrophy" at the beginning of illness.Therefore, idiopathic myositis autoantibody should be examined to confirm the diagnosis for children suspected to be " muscular dystrophy" but not confirmed by genetic examination.
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OBJECTIVE@#To investigate the classification of idiopathic inflammatory myopathies (IIM) based on clinical manifestations and myositis- specific antibodies using cluster analysis.@*METHODS@#We retrospectively analyzed the data of patients with IIM admitted in Nanfang Hospital in 2015-2019. The clinical data of the patients including serum creatine kinase (CK), interstitial lung disease (ILD), cancer, and myositis-specific antibodies were collected for two-step cluster analysis to identify the distinct clusters of patients, whose clinical characteristics were subsequently analysed.@*RESULTS@#A total of 71 patients with IIM were included in this study, including 30 (42.3%) with polymyositis (PM), 20 (28.2%) with classic dermatomyositis (DM), 16 (22.5%) with amyopathic dermatomyositis (CADM), and 5 (7.0%) with immune-mediated necrotizing myopathy (IMNM). Two-step cluster analysis identified 3 distinctive subgroups: Cluster 1 of 15 (51.7%) patients characterized by rash, positive anti-MDA5 antibody and hypoproteinemia ( < 0.05) with normal or slightly elevated CK level, mainly corresponding to CADM; Cluster 2 of 4 (57.1%) patients with significantly elevated CK and positive anti-SRP antibody ( < 0.001) corresponding to IMNM; and Cluster 3 of 17 (48.6%) patients consisting primarily of patients with PM, characterized by positivity for anti- aminoacyl transfer RNA synthetases antibodies (=0.022) corresponding to antisynthetase syndrome (ASS).@*CONCLUSIONS@#Patients with IIM can be divided into 3 subgroups based on their clinical and serological characteristics (especially myositis-specific antibodies), and among them ASS may represent an independent IIM subgroup with unique clinical characteristics.
Subject(s)
Humans , Antibodies , Autoantibodies , Dermatomyositis , Lung Diseases, Interstitial , Myositis , Retrospective StudiesABSTRACT
Idiopathic inflammatory myopathies (IIM) are a group of acquired immune myopathy,which mainly include polymyositis,dermatomyositis,amyopathic dermatomyositis,sporadic inclusion body myosistis (sIBM) and immune-mediated necrotizing myopathy,as well as some special types of antisynthetase syndrome,anti-signal recognition particle antibody positive necrotizing myopathy (NM),anti-3-hydroxy-3-methylglutaryl-coenzyme A reductase antibody positive NM.The diagnosis of these different types of IIM mainly depends on clinical manifestations,antibody detection and muscle pathological techniques.Different types of IIM have different clinical manifestations,or overlapping manifestations.This article systematically describes the evolution of IIM types,the main antibodies to myositis,the pathological characteristics of muscles,the manifestations of various types and the treatment of myositis.In addition to sIBM,patients with most of the other types of IIM have good outcomes by early diagnosis,timely,correct and adequate drug treatment.
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Objective To characterize the clinical,electrophysiology and neuropathological features of 4 cases with immune-mediated necrotizing myopathy (IMNM).Methods We retrospectively analyzed the clinical,electrophysiology,neuropathological characteristics of 4 IMNM patients with muscular and skin biopsy in our department during 4 years (from January 2011 to January 2014).Results Among these 4 patients,2 were men and 2 were women (aged 37 to 58 years) with disease duration ranging from 1 month to 60 months.Two patients were with acute onset and 2 with chronic onset.All 4 patients had proximal muscle weakness with three patients with cervical flexor muscle weakness and one with respiratory muscles weakness and noninvasive ventilator assisted respiration.One patient had interstitial lung disease.The anti-signal recognition particle antibodies were strong positive in all 4 patients.Muscle biopsy showed group necrotizing and regenerating fibers in one patient and few scattered necrotizing and regenerating fibers in the other 3 patients.Both muscle fiber hypertrophy and muscle fiber atrophy together with proliferation of connective tissue on endomysium could be viewed in all 4 patients.However,very few inflammatory cells were detectable in patients.One patient was treated with corticosteroids and the other three were treated with combination of corticosteroids and immunosuppressant drugs.Conclusions IMNM is characterized by heterogeneity at disease onset,severity and ilnvolvement of muscles with,however,similary pathological changes including the presence of numerous necrotic and regenerating fibers with little or none inflammation.Corticosteroid and/or immunosuppressant is effective for patients.