Diagnosis Of Inflammatory Myopathies Research Articles

In inflammatory myopathies, dropped head/bent spine syndrome is associated with scleromyositis: an international case–control study

BackgroundSome myopathies can lead to dropped head or bent spine syndrome (DH/BS). The significance of this symptom has not been studied in inflammatory myopathies (IM).ObjectivesTo assess the significance of DH/BS...

N-CAM Expression: The Study of Muscle Disease in a Tertiary Center of Thailand

Background: Neural cell adhesion molecule (N-CAM), or CD56, is a cell-surface glycoprotein that plays a critical role in mediating intercellular adhesion in the central nervous system. It is also found to be expressed on embryonic muscle but disappears in healthy adult muscle. However, denervated or regenerating muscles can express N-CAM. Objective: To evaluate the value of N-CAM expressions in diagnosing muscle diseases in the Thai population. Materials and Methods: The present study used immunohistochemistry to interpret N-CAM expression in 75 muscle biopsy specimens diagnosed with myopathies and non-myopathies from a 3-year retrospective cohort. Results: Using the chi-squared test, there was statistically significant associativity between N-CAM expression and the diagnosis of inflammatory myopathy, but not in muscular dystrophy, neurogenic change, or non-specific myopathy even though they also showed N-CAM expression. The inflammatory myopathy showed positive N-CAM in 15 out of 17 cases with statistical significance (p<0.001, OR 14.250, 95% CI 2.960 to 68.606). The authors did not find any N-CAM expression in the present study mitochondrial myopathy or non-myopathy cases, whose biopsies were defined as a control group due to lack of myopathic change and non-specific clinical symptoms. Conclusion: The authors suggest the evaluation of N-CAM expression as a complementary tool in the diagnosis of muscle diseases that have denervated or regenerating muscle fibers, especially in inflammatory myopathy. Keywords: Neural cell adhesion molecule; N-CAM; CD56; Muscle disease; Myopathy

Evolving classification and role of muscle biopsy in diagnosis of inflammatory myopathies.

Idiopathic inflammatory myopathy (IIM) is a broad term that includes dermatomyositis, polymyositis, overlap myositis, sporadic inclusion body myositis, and immune-mediated necrotizing myopathy. The understanding of the pathogenesis of IIM is ever-evolving with regular updates in the classification schema. With the recognition of autoantibodies and their detection, the diagnostic algorithms are changing in favor of non-invasive diagnoses. However, muscle biopsy has immensely contributed to our understanding of the pathogenesis of inflammatory myopathies, and the pathologic features of different subtypes are well established. The biopsy also aids in distinguishing myopathies with overlapping clinical features, particularly dystrophies, which can show inflammation on biopsy in some cases. In this article, the various classification schemes of the IIM are reviewed. Also, the pathogenesis and pathology of each type of IIM have been highlighted. This article emphasizes the role of muscle biopsy in the diagnosis of inflammatory myopathies.

Current approach to diagnosis of inflammatory myopathies: Clinical features and myositis antibody profiles.

Diagnosis of inflammatory myositis has been made easier with the availability of commercial assays for myositis-specific and myositis-associated antibodies. Clinico-serological association studies have permitted a better definition of clinical subsets. Myositis-specific auto-antibodies are highly specific and non-overlapping, whereas myositis-associated antibodies are those seen also in other connective tissue disorders such as systemic lupus erythematosus, primary Sjogren's syndrome, and idiopathic pulmonary auto-immune fibrosis. Their value is pronounced when clinical features are subtle or non-specific or when the muscle is not the primary organ involved. Overall, the muscle-specific and myositis-associated antibodies have changed the landscape in terms of diagnostic utility, prognostication, and the approach to organ-specific evaluation and management of idiopathic inflammatory myopathies (IIMs).

P067 Covid- 19 infection as a trigger for immune inflammatory myositis

Abstract Background/Aims Increasing experience in managing patients with COVID-19 infection has demonstrated the development of autoimmune phenomena following infection. We describe a patient with preceding COVID-19 infection who presented with inflammatory immune myositis, positive myositis antibodies and a normal creatine kinase. Methods N/A Results A 61-year-old Caucasian female presented feeling generally unwell and with weakness. She had COVID-19 infection 4 months prior, which necessitated admission to the Intensive Care Unit (ITU), treatment with dexamethasone and oxygen and subsequent discharge with home continuous positive airway pressure (CPAP). Other co-morbidities included atrial fibrillation, chronic kidney disease stage three, hypertension, obesity, recent pulmonary embolism, obstructive sleep apnoea, chronic lymphoedema and hypercholesterolaemia on atorvastatin. Her mobility had been gradually reducing over the previous months to now requiring a wheelchair. Neurological examination demonstrated bilateral proximal lower limb weakness, power 3/5 and an unsafe swallow, for which a naso-gastric tube was inserted. A non-specific erythematous pruritic rash was noted on the arms. Full body Computerised tomography (CT) and Magnetic Resonance Imaging (MRI) of the brain and spine were unremarkable. Creatinine kinase (CK) was within normal limits at 81, and C-reactive protein (CRP) was mildly raised at 36. C3 was low at 0.67 and C4 low at 0.03. Cryoglobulins were not detected. She was positive for antinuclear antibody (ANA) (1:320 titre), Ro-52, PM-Scl75, and anti-La. Anti-dsDNA was negative. Electromyography could not be performed due to the presence of chronic lymphoedema. MRI showed symmetrical STIR hyperintense signal changes in the quadriceps muscles bilaterally. A muscle biopsy showed a small focus of mild lymphocyte infiltration in the endomysial connective tissue, mild increase in acid phosphatase expression in many fibres in dotlike pattern, overexpression of HLA-ABC with deposits of complement found in in endomysial capillaries, consistent with a diagnosis of inflammatory myopathy. Following commenced of 60 mg prednisolone daily, there was a marked improvement in swallowing and the NG tube was removed. A positron emission tomography (PET) scan showed non-specific marrow, splenic and adrenal hyperplasia. The patient was then started on mycophenolate mofetil (MMF), but was switched to azathioprine due to side effects. On review following discharge, the patient continues to require a wheelchair to mobilise, but there has been improvement in her swallow and she reports feeling better within herself. Conclusion Inflammatory myositis is a rare sequela of COVID-19 infection. The development of myositis-specific antibodies post infection has previously been described. This case highlights the significant dysphagia and debility despite a normal CK and the need for a high index of suspicion. Possible triggers of an inflammatory response predisposing to autoimmune phenomena include molecular mimicry, bystander activation, exposure of previously hidden epitopes to activated T cells, activation of Toll-like receptors and activation of the complement system. Disclosure G. Bartminski: None. A. Vijayan: None. K. Beharry: None. D. De Lord: None.

Maternal and neonatal outcomes among pregnant women with inflammatory myopathies.

Pregnancy outcomes in women with inflammatory myopathies (IM) are not well studied. The purpose of this study is to evaluate the effects of IM on maternal and neonatal outcomes. We conducted a retrospective cohort study using data from the Healthcare Cost and Utilization Project- Nationwide Inpatient Sample (HCUP-NIS) from 1999 to 2015. Among all pregnant women who delivered during this period, those with a diagnosis of IM were identified using the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) coding, which included all patients with dermatomyositis and polymyositis. Maternal and neonatal outcomes were compared in pregnant women with and without IM. Multivariate logistic regression analysis was used to estimate the adjusted effects of IM on these outcomes. A total of 13,792,544 pregnant women delivered between 1999 and 2015, of which 308 had a diagnosis of IM, for an overall prevalence of 2 per 100,000 pregnant women, with rates increasing over the study period. Pregnant women with IM were more likely to be older, African American and suffer from other autoimmune connective tissue diseases. IM in pregnancy was associated with greater risk of preeclampsia, caesarean delivery, major postpartum infections, urinary tract infections and longer hospital stay. Neonates born to mothers with IM had greater risk of prematurity, small for gestational age and intrauterine fetal demise. Pregnant women with IM are at higher risk of adverse maternal and neonatal outcomes and should be closely followed in specialized centers with collaboration between maternal-fetal medicine and rheumatology.

Dermatomyositis: Muscle Pathology According to Antibody Subtypes.

Background and ObjectivesDiscoveries of dermatomyositis-specific antibodies (DMSAs) in patients with dermatomyositis raised awareness of various myopathologic features among antibody subtypes. However, only perifascicular atrophy and perifascicular myxovirus resistant protein A (MxA) overexpression were officially included as definitive pathologic criteria for dermatomyositis classification. We aimed to demonstrate myopathologic features in MxA-positive dermatomyositis to determine characteristic myopathologic features in different DMSA subtypes.MethodsWe performed a retrospective pathology review of muscle biopsies of patients with dermatomyositis diagnosed between January 2009 and December 2020 in a tertiary laboratory for muscle diseases. We included all muscle biopsies with sarcoplasmic expression for MxA and seropositivity for DMSAs. MxA-positive muscle biopsies that tested negative for all DMSAs were included as seronegative dermatomyositis. We evaluated histologic features stratified according to 4 pathology domains (muscle fiber, inflammatory, vascular, and connective tissue) and histologic features of interest by histochemistry, enzyme histochemistry, and immunohistochemical study commonly used in the diagnosis of inflammatory myopathy. We performed ultrastructural studies of 54 available specimens.ResultsA total of 256 patients were included. Of these, 249 patients were positive for 1 of the 5 DMSAs (seropositive patients: 87 anti–transcription intermediary factor 1-γ [TIF1-γ], 40 anti–complex nucleosome remodeling histone deacetylase [Mi-2], 29 anti–melanoma differentiation gene 5 [MDA5], 83 anti–nuclear matrix protein 2 [NXP-2], and 10 anti–small ubiquitin-like modifier-activating enzyme [SAE] dermatomyositis) and 7 patients were negative for all 5 DMSAs (seronegative patients). Characteristic myopathologic features in each DMSA subtype were as follows: anti-TIF1-γ with vacuolated/punched out fibers (64.7%; p < 0.001) and perifascicular enhancement in HLA-ABC stain (75.9%; p < 0.001); anti-Mi-2 with prominent muscle fiber damage (score 4.9 ± 2.1; p < 0.001), inflammatory cell infiltration (score 8.0 ± 3.0; p = 0.002), perifascicular atrophy (67.5%; p = 0.02), perifascicular necrosis (52.5%; p < 0.001), increased perimysial alkaline phosphatase activity (70.0%; p < 0.001), central necrotic peripheral regenerating fibers (45.0%; p = 0.002), and sarcolemmal membrane attack complex deposition (67.5%; p < 0.001); anti-MDA5 with scattered/diffuse staining pattern of MxA (65.5%; p < 0.001) with less muscle pathology and inflammatory features; anti-NXP-2 with microinfarction (26.5%; p < 0.001); and anti-SAE and seronegative dermatomyositis with HLA-DR expression (50.0%; p = 0.02 and 57.1%; p = 0.02, respectively).DiscussionWe describe a comprehensive serologic–pathologic correlation of dermatomyositis primarily using MxA expression as an inclusion criterion. In our study, DMSAs were associated with distinctive myopathologic features suggesting different underlying pathobiologic mechanisms in each subtype.

Myositis autoantibodies in Iranian myositis patients: assessment the frequency and clinical relevancy.

Dermatomyositis (DM) and polymyositis (PM) are known as two major types of idiopathic inflammatory myopathies (IMMs). During the past years, growing data strongly suggest the clinical significance of myositis-associated autoantibodies (MAAs) and myositis-specific autoantibodies (MSAs). The present study aimed to determine the profile of MSAs and MAAs, subsequently to address the clinical significance of these autoantibodies in Iranian myositis patients. In this cross-sectional study, 28 DM and 24 PM patients were entered. Demographic and clinical characteristics were collected by direct examination and patients' medical record. The existence of MSAs and MAAs was assessed by indirect immunofluorescence then using immunoblotting (FA 1510-1005-1, DL 1530-1601-4 G; Euroimmun, Germany). Data were analyzed using the SPSS software (v22; SPSS Inc. Chicago, IL, USA). The mean age of the patients was 46.18 ± 12.95years and male/female ratio was 28.8/71.2. Autoantibodies were positive in 63.46% of myositis patients. Interestingly, anti-TIF1γ and anti-PL7 were significantly associated with malignancy (P < 0.001, P = 0.008; respectively). The existence of autoantibody and anti-Jo1 had significant relation with interstitial lung disease (ILD) (P = 0.034, P = 0.006; respectively). Joint involvements including arthritis and arthralgia were significantly associated with anti-Ro52 and anti-Jo1 (P = 0.04, P = 0.02; respectively). Taken together, it can be concluded that certain myositis autoantibodies present clinical significance which is in line with the literature. The use of these autoantibodies as biomarkers by line blotting along with indirect immunofluorescence facilitates diagnosis of inflammatory myopathies and makes it more accurate as well as better management of myositis patients if used based on a science-based manner. Key Points • Identification of MSAs and MAAs facilitates the diagnosis of inflammatory myopathies and provides better myositis patient's management if used according to a science-based manner. • Anti-rod and ring antibody was detected in a patient with ovarian cancer-induced dermatomyositis. • Malignancy and ILD are integrated parts of myositis which can be associated with MSAs and MAAs.

Inflammatory myopathies associated with myelodysplastic syndromes: A French multicenter case control study and literature review

ObjectivePatients with inflammatory myopathies (IM) are known to have an increased risk of developing malignancies. Autoimmune and inflammatory diseases occur in up to 25% of patients with myelodysplastic syndrome (MDS). This study aimed to describe the rare association between IM and MDS. MethodsWe report here the main characteristics, treatment, and outcome of 21 patients (11 national cases and 10 additional cases from a literature review) with IM associated to MDS. ResultsMedian age of patients at IM diagnosis was 66 years (range 26 – 78). Diagnosis of the two conditions were concomitant in most patients (n=14/21) whereas MDS diagnosis preceded IM diagnosis in 5 patients. Different types of IM were observed but dermatomyositis was the most frequent (59%). Compared to IM without MDS (IM/MDS−), patients with MDS (IM/MDS+) were older (median 66 vs 55, p=0.3), more frequently male (sex ratio M/F 1.125 vs 0.41, p=0.14) and positive for anti-TIF1γ (24% vs 4%, p=0.0039). Antisynthetase syndrome was never observed among IM/MDS+ patients (0% vs 28%, p=0.01). MDS WHO type was not univocal, but the prognostic score was of low risk in almost all cases. IM was usually steroid sensitive (82% of patients) but often steroid dependent (56% of patients). Overall survival of IM patients with MDS was worse compared to patients with IM without MDS (p=0.0002). ConclusionIM associated with MDS are mainly represented by dermatomyositis and/or anti-TIF1γ autoantibodies. Antisynthetase syndrome has not been described in association with MDS. Despite low-risk MDS, overall survival of IM patients with MDS is worse than IM patients without MDS.

Idiopathic Inflammatory Myopathies (IIMs)

Diagnosis of inflammatory myopathy are usually based on clinical examination and histopathology of the muscles and muscle biopsy, usually guided by PET-CT. This is not uncommonly presented by extramacular signs like interstitial lung disease, dysphagia, few skin signs, loss of weight, arteritis, cardiomyopathy, Pulmonary hypertension, respiratory failure, and cancer.

Métodos de diagnóstico en el estudio de las Miopatías Inflamatorias Autoinmunes

The Idiopathic Inflammatory Myopathies (IIM) comprise a heterogeneous group of acquired muscle diseases classified as polymyositis (PM), dermatomyositis (DM), Inclusion Body Myositis(IBM), ImmunoMediated Necrotizing Myopathies, (IMNM), Overlap Myositis(OM), juvenile myositis, Antisynthethase Syndrome (ASS) and cancer related myositis(CAM). The presence of myositis specific antibodies in the serum and autoantibodies against target antigens and inflammatory infiltrates in muscle tissue suggests the autoimmune condition of the disease. The diagnosis of inflammatory myopathies is often a challenge and the disposal of diagnostic tools are not always available in daily practice. Information on the accessibility of these methods was obtained from the Argentine Register of Myopathies. The study of muscle enzymes, ANA, anti-Jo-1 antibodies and chest tomography were easy to get to most patients while muscle MRI, lung diffusion capacity for carbon monoxide (DLco%) and muscle biopsy were performed in less than 50% of cases. Other myositis specific antibodies, necessary for disease diagnosis and prognosis, were mostly done through a subsidy from the Argentine Rheumatology Society.

Inflammatory Myopathy-Related Interstitial Lung Disease: From Pathophysiology to Treatment

Inflammatory myopathies (IM) are auto-immune connective tissue diseases characterized by muscle involvement and by extramuscular manifestations. As such, pulmonary manifestations, which mainly include interstitial lung disease (ILD), often darken two out of four distinct IM, namely dermatomyositis and overlapping myositis. Being the initiation site of the disease and being the leading cause of morbidity and mortality, ILD is of major importance in this context. ILD has a heterogeneous expression among the patients, with various onset mode, various radiological pattern, various severity and finally with different prognoses, which are particularly difficult to predict at the time of IM diagnosis. Therefore, ILD is a challenging issue. Treatments are based on steroids and immunosuppressive or targeted therapies. Their respective place is yet poorly codified however and remains often based on clinician expertise. Dedicated clinical trials are lacking to date and are also difficult to build, due to difficulty of constituting large and homogeneous patient groups and to rigorously evaluate disease outcomes. Indeed, pulmonary function tests alone are being regularly defeated in IM, in which respiratory muscles are often involved. Composite scores, bringing together several lung parameters, should thus be developed and validated in the future, to better assess the disease response to treatment. This review aims to describe the current knowledge of IM immuno-pathogenesis, the clinical features associated with IM related-ILD, focusing of both severity and prognosis, and the actual therapeutic approaches.

CEUS-application possibilities in the musculoskeletal system

Contrast-enhanced ultrasound (CEUS) offers easily accessible visualization and quantification of the skeletal muscle microcirculation and other tissues in vivo and in real-time with almost no side effects. The aim of this review is to present the increasing number of musculoskeletal CEUS applications. CEUS applications regarding the musculoskeletal system include applications at bone and joints extending beyond the visualization of only the muscular microcirculation. Besides basic muscle physiology, impaired microcirculation in patients with peripheral artery disease or diabetes mellitus and the diagnosis of inflammatory myopathies have been the subject of previous CEUS studies. More recent studies in orthopedics and traumatology have focused on osseous and muscular perfusion characteristics, e. g., in differentiating infected and aseptic non-unions or the impact of different types of implants and prostheses on muscular microcirculation as a surrogate marker of clinical success. CEUS of the musculoskeletal system is used in clinical trials or off-label. Therefore, it is not well established in clinical routine. However, considering the increasing number of musculoskeletal CEUS applications, this could change in the future.

Dermatomyositis panniculitis: a clinicopathological and immunohistochemical study of 18 cases.

Panniculitis occurring in dermatomyositis is uncommon, with only a few cases described in the literature, most of them as case reports. This report describes the clinicopathological and immunohistochemical findings in a series of 18 patients with panniculitis associated with dermatomyositis. In each patient, we collected the clinical data of the cutaneous lesions as well as the characteristic clinical and laboratory findings. A series of histopathologic findings was recorded in the biopsy of each patient. A panel of antibodies was used in some cases to investigate the immunophenotype of the infiltrate. Data of treatment and follow-up were also collected. Of the 18 patients, 13 were female and 5 were male, ranging in age from 13 to 74 years (median, 46.4 years). In addition to panniculitis, all patients presented pathognomonic cutaneous findings of DM and reported proximal muscle weakness prior to the diagnosis of panniculitis. Muscle biopsy was performed in 17 patients and MRI in one, all with the diagnosis of inflammatory myopathy. None of the patients presented any associated neoplasia. Panniculitis lesions were located in the upper or lower limbs. Histopathology showed a mostly lobular panniculitis with lymphocytes as the main component of the infiltrate. Most cases showed also numerous plasma cells and lymphocytes surrounding necrotic adipocytes (rimming) were frequently seen. Lymphocytic vasculitis and abundant mucin interstitially deposited between collagen bundles of the dermis were also frequent findings. Late-stage lesions showed hyaline necrosis of the fat lobule and calcification. Immunohistochemistry demonstrated that most lymphocytes of the infiltrate were T-helper lymphocytes, with some B lymphocytes in the lymphoid aggregates and small clusters of CD-123-positive plasmacytoid dendritic cells in the involved fat lobule. Panniculitis in dermatomyositis is rare. Histopathologic findings of panniculitis dermatomyositis are identical to those of lupus panniculitis. Therefore, the final diagnosis requires clinic-pathologic correlation.

Inflammatory myopathies: A new landscape

Greater accuracy in clinical descriptions combined with advances in muscle histology and immunology have established that inflammatory myopathies (IMs), similarly to inflammatory rheumatic diseases, constitute a highly heterogeneous group of conditions. The topographic distribution, severity, and tempo of onset of the myopathy vary widely, and the histological findings distinguish at least five different profiles, which may reflect different pathophysiological processes. Most IMs are connective tissue diseases that can affect multiple organs, among which the most common targets are the skin, joints, and lungs. The extramuscular manifestations may antedate the muscular involvement and should therefore suggest a diagnosis of IM even in the absence of obvious muscle disease. About 20 different autoantibodies have been identified in patients with IM. Some are mutually exclusive and associated with specific combinations of clinical manifestations. Following the model of antisynthetase syndrome, about 10 syndromes associated with autoantibodies specific of IM have been identified. Thus, polymyositis is now emerging as a rare entity that is often mistaken for more recently described patterns of IM. No consensus exists to date about the classification of IMs. Nevertheless, the clinical manifestations, autoantibody profile, and muscle histology can be used to distinguish patient subgroups with fairly homogeneous patterns of complications, treatment responses, and outcomes. These subgroups are also characterized by specific genetic and environmental factors. The advances made in the nosology of IMs have benefited the diagnosis, personalization of treatment strategies, and understanding of pathophysiological mechanisms. They can be expected to assist in the development of specific treatments.

Meeting the challenges in the diagnosis of inflammatory myopathies.

Inflammatory myopathy (IM) is a rubric term to describe a heterogeneous group of muscle diseases typified by dermatomyositis and polymyositis. The current classifications are unsatisfactory, but IM associated with other connective tissue diseases (CTDs), such as systemic lupus erythematosus, underlying malignancy and HIV, should also be included. Although uncommon, IM should always be considered in a patient who presents with proximal weakness of gradual onset and has raised serum muscle enzymes. The diagnosis may be obvious if the patient has diagnostic skin signs such as heliotropic rash (peri-orbital discoloration) and Gottron’s lesions (typically on the extensor surfaces of the fingers). In the absence of obvious skin manifestations, other features of a CTD such as Raynaud’s phenomenon, abnormal capilloroscopy and the presence of serum antinuclear factor antibody should be searched for. Conditions that mimic IM include other causes of myopathy such as endocrine disorders, adverse effects of medication, metabolic myopathies and muscle dystrophies. Atypical features suggesting an alternative diagnosis are acute onset, severe pain, asymmetrical involvement, distal weakness and wasting. Appropriate investigations include a chest radiograph indicating interstitial lung disease or malignancy. Electromyography and muscle biopsy are useful in cases where other diagnoses are suspected.

I.I.7 - Contribution of myopathological analysis to myositis classification in a multidisciplinary approach

Diagnosis of inflammatory myopathies is based on evaluation of a certain clinical syndrome, laboratory results, electromyography and the myopathological assessment of a muscle biopsy. Recently, several additional parameters have been taken into consideration; among these, serological auto-antibody testing is the most relevant. The current classification of inflammatory myopathies (IIMs) comprises polymyositis (PM), dermatomyositis (DM), immune-mediated necrotizing myopathy (IMNM), sporadic inclusion body myositis (sIBM), and non-specific myositis (NSM). This classification has been a subject of intense critique at various levels. First, the entity of polymyositis has been questioned, since many of these patients developed either sIBM later on, or should better be grouped among the IMNM group or the NSM/overlap myositis group. Second, dermatomyositis encompasses a multitude of subgroups with different clinical, therapeutical and prognostic implications. It has been shown recently that certain subgroups can be defined by different myositis specific auto-antibodies, such as TIF1γ, Mi-2, NXP2 or MDA-5. Anti-TIF1γ+ and NXP2+ adult patients show an increased risk of systemic malignancy, while anti-Mi-2+ patients harbour a classical dermatomyositis with good response to treatment, and NXP2+ juvenile DM patients have a strongly increased risk of developing calcinosis. The morphology and in situ immune mechanisms of the skeletal muscle of these subentities are presented. Third, necrotizing myopathy was recently added to the IIMs; however, IMNM still comprises a heterogeneous group of diseases. Recently interesting advances have been achieved, illuminating the immunopathogenesis from anti-SRP+, anti-HMGCR+ patients and anti-synthetase syndrome-associated myositis. These entities will be discussed in the light of clinical, serological, morphological and immunological characteristics.

Myositiden

This article gives a review of the classification, diagnostic procedures and treatment of idiopathic inflammatory myopathies from a neurological point of view. The myositis syndromes can be subdivided into four groups, polymyositis (PM), dermatomyositis (DM), inclusion body myositis (IBM) and necrotizing myopathy (NM), which substantially differ clinically and pathophysiologically. Myositis may also occur in association with cancer or autoimmune systemic diseases (overlap syndrome). Diagnosis of inflammatory myopathies is based on clinical symptoms, determination of creatine phosphokinase and acute phase parameters in blood (e.g. C-reactive protein and erythrocyte sedimentation rate), electromyography results and findings of magnetic resonance imaging (MRI) in muscle. A muscle biopsy is mandatory to confirm the diagnosis. High quality randomized controlled trials of treatment regimens for inflammatory myopathies are sparse; however, empirical experience indicates a clear effectiveness of immunosuppressive treatment of PM, DM and NM.

G.P.79: An analysis of the sensitivity and specificity of MHC-I and MHC-II immunohistochemical staining in muscle biopsies for the diagnosis of inflammatory myopathies

Although there have been several previous reports of immunohistochemical staining for MHC antigens in muscle biopsies, there appears to be a lack of consensus about its routine use in the diagnostic evaluation of patients with suspected inflammatory myopathy (IM). Positive MHC-I staining is non-specific but is widely used as a marker for IM, while the role of MHC-II staining is not clearly defined. We investigated the sensitivity and specificity of MHC-I and II for the diagnosis of IIM in 432 biopsies from a single reference laboratory (186 cases of IIM and 246 cases of non-inflammatory myopathies (NIM) and other neuromuscular disorders). MHC-I showed a very high sensitivity (0.984) in patients with IM and very low specificity (0.071). On the other hand, MHC-II showed a high specificity (0.908) and moderate sensitivity (0.605) in all major subgroups of IM especially inclusion body myositis. When only MHC-I was taken into consideration, the area under the ROC curve was 0.53 and increased to 0.762 (SE: 0.024; <i>p</i><0.001) when MHC-II staining was added. In the IM group there was a significant association between MHC-II positivity and infiltrates (<i>p</i>=0.014). The findings indicate that the combination of MHC-I and MHC-II staining results in a higher degree of specificity for the diagnosis of IM and that in biopsies with inflammation, positive MHC-II staining strongly supports the diagnosis of an immune-mediated myopathy. We recommend that immunohistochemical staining for both MHC-I and MHC-II should be included routinely in the evaluation of muscle biopsies from patients with suspected IM. However, as the interpretation of MHC staining is very dependent on the technique used, further studies are needed to compare procedures in different centres and develop standardised protocols.

THU0243 Standardized mortality ratios and predictors of survival in 215 southern chinese patients with inflammatory myopathies

ObjectivesTo examine the standardized mortality ratios (SMRs) and predictive factors for malignancy in a cohort of southern Chinese patients with inflammatory myopathies (IM).MethodsAll patients who were diagnosed to have polymyositis...