Pitfalls in the diagnosis of myositis

Publication date: Available online 13 February 2020Source: Best Practice &Research Clinical RheumatologyAuthor(s): Hector Chinoy, James B. LillekerAbstractThe idiopathic inflammatory myopathies are a group of heterogeneous autoimmune connective tissue diseases. Despite increase in the understanding of these conditions, securing a timely diagnosis and accurate subtype classification remains difficult in some cases. This has important implications for patients, where delayed or inappropriate treatments can have a negative effect on outcomes.Several conditions can mimic myositis, including metabolic myopathies, genetic myopathies and neurological disease. In addition, the heterogeneity within the idiopathic inflammatory myopathy spectrum can also create diagnostic confusion, referred to here as ‘myositis chameleons’. This includes inclusion body myositis, immune-mediated necrotizing myopathy, hypomyopathic variants of anti-synthetase syndrome and overlap disease.We highlight the importance of a thorough diagnostic workup, refer to updated classification criteria and emphasize the importance of myositis autoantibody testing. Where diagnostic doubt exists, the involvement of a specialist centre and a multidisciplinary team is vital.
Source: Best Practice and Research Clinical Rheumatology - Category: Rheumatology Source Type: research

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The idiopathic inflammatory myopathies (IIMs) are a group of systemic autoimmune diseases characterised primarily by muscle inflammation but also potentially accompanied by a range of extra-muscular manifestations. Dermatomyositis (DM), polymyositis (PM) and inclusion body myositis (IBM) constitute well-characterised subtypes of IIM, with the entity of non-specific idiopathic inflammatory myopathy (NSIIM) being more recently described [1]. Whilst these IIM subtypes are distinguished on clinical, serological and histological grounds, they are unified by the presence of a typically prominent intramuscular lymphocytic infiltrate.
Source: Neuromuscular Disorders - Category: Neurology Authors: Source Type: research
Fundamental obstacles to the development of therapies for sporadic inclusion body myositis (IBM) include our limited understanding of disease pathogenesis as well as a lack of animal models. The primary invasion of myofibers by CD8+ T cells, an increased association of IBM with specific HLA haplotypes and other autoimmune diseases, and the presence of autoantibodies in many patients suggests that IBM is primarily an autoimmune disease. However, an association with aging, a lack of response to immunotherapy, and presence of ubiquitinated protein aggregates suggest the immune response may be secondary to myodegeneration.
Source: Neuromuscular Disorders - Category: Neurology Authors: Source Type: research
Myasthenia gravis (MG) is an autoimmune disorder caused by antibodies targeting the neuromuscular junction, which in most cases are directed towards the skeletal muscle acetylcholine receptor (AChR) [1]. The pathophysiology of MG is accepted to be immune mediated [2]. Sporadic inclusion body myositis (IBM) is considered the most common inflammatory myopathy in patients over 50 years old, but its pathophysiology remains to this day an enigma: It is still unclear whether it is a primary degenerative disease with secondary dysimmune reaction or vice versa [3].
Source: Neuromuscular Disorders - Category: Neurology Authors: Tags: Case report Source Type: research
We examined inclusion body myositis muscle T-cell proliferation by Ki67 immunohistochemistry demonstrating that diseased muscle-invading T cells are minimally or non-proliferative, in accordance with known properties of highly differentiated or terminally differentiated T cells. We found low expression of KLRG1 on infection-protective human lymphoid tissue central memory T cells and autoimmune-protective human blood regulatory T cells. Targeting highly differentiated cytotoxic T cells could be a favourable approach to treatment of inclusion body myositis.
Source: Brain - Category: Neurology Source Type: research
Source: The American Journal of Medicine - Category: General Medicine Authors: Tags: Clinical Communication to the Editor Source Type: research
Osman K. Yilmaz1, Stefanie Haeberle1, Meifeng Zhang1, Marvin J. Fritzler2, Alexander H. Enk1 and Eva N. Hadaschik1,3* 1Department of Dermatology, University of Heidelberg, Heidelberg, Germany 2Mitogen Advanced Diagnostics Laboratory, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada 3Department of Dermatology, University Hospital of Essen, Essen, Germany Due to a missense mutation in the Foxp3 gene, scurfy mice are deficient in functional regulatory T cells (Treg). The consequent loss of peripheral tolerance manifests itself by fatal autoimmune mediated multi-organ disease. Previous studies...
Source: Frontiers in Immunology - Category: Allergy & Immunology Source Type: research
The objectives of our study were to determine the sensitivity and specificity of anti-NT5c1A for sIBM, demonstrate demographic, clinical and serological predictors for anti-NT5c1A positivity and determine if anti-nuclear antibody (ANA) indirect immunofluorescence (IIF) staining on HEp-2 cells is a reliable screening method for anti-NT5c1A. Methods: Sera from sIBM patients and controls were stored at −80°C until required for analysis. IgG antibodies to NT5c1A were detected by an addressable laser bead immunoassay (ALBIA) using a full-length human recombinant protein. Autoantibodies to other autoimmune myopathy an...
Source: Frontiers in Immunology - Category: Allergy & Immunology Source Type: research
Idiopathic inflammatory myopathies are a group of autoimmune diseases that are characterized by muscle inflammation resulting in elevated muscle enzyme release and distinctive biopsy findings. This group of conditions includes polymyositis, dermatomyositis, inclusion body myositis, and necrotizing autoimmune myopathy. Although they have many similarities, the inflammatory myopathies differ in their clinical, pathological, and treatment realms. Extramuscular manifestations may involve many organs that include the skin, joints, heart, lungs, and gastrointestinal tract. Cardiovascular involvement is one of the leading causes ...
Source: Cardiology in Review - Category: Cardiology Tags: Review Articles Source Type: research
AbstractWe discuss a challenging case of a 58-year-old Vietnamese-American woman who presented to her new primary care provider with an 8-year history of slowly progressive dysphagia, hoarseness, muscle weakness with associated frequent falls, and weight loss. She eventually reported dry eyes and dry mouth, and she was diagnosed with Sjogren ’s syndrome. Subsequently, she was additionally diagnosed with inclusion body myositis and gastric light-chain (AL) amyloidosis. Although inclusion body myositis has been previously associated with Sjogren’s syndrome, inclusion body myositis is rare in non-Caucasians, and t...
Source: Journal of General Internal Medicine - Category: Internal Medicine Source Type: research
Conclusions Normal muscle contains a considerable number of macrophages and T-lymphocytes. Muscle biopsy is likely to detect inflammatory changes in patients with myalgia or hyperCKemia only if pathologic EMG findings are present.
Source: Neurology Neuroimmunology and Neuroinflammation - Category: Neurology Authors: Tags: Autoimmune diseases, Muscle disease, EMG Article Source Type: research
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