Idiopathic inflammatory myopathies – a guide to subtypes, diagnostic approach and treatment

Abstract

The idiopathic infl ammatory myopathies are a group of conditions characterised by infl ammation of muscles (myositis) and other body systems. The diagnosis can be challenging because of the many potential clinical features and extra-muscular manifestations, which may be seemingly unrelated. An accurate diagnosis requires up-to-date understanding of the clinical manifestations, different clinical subtypes and appropriate interpretation of investigations, including newly described serological subtypes. This review will detail the approach to the diagnosis of an idiopathic infl ammatory myopathy, based on up-to-date knowledge. The recently updated classifi cation criteria and treatment options will also be described.

Management of the idiopathic inflammatory myopathies

“…In dermatomyositis, the presence of autoantibodies leads to subsequent complement activation and is largely driven by a humoral-mediated immune response. 1 In contrast, polymyositis and inclusion body myositis are driven by a CD8 + cytotoxic T cell response. 1 As with many autoimmune rheumatological conditions, genes within the…”

“…1 In contrast, polymyositis and inclusion body myositis are driven by a CD8 + cytotoxic T cell response. 1 As with many autoimmune rheumatological conditions, genes within the…”

“…6 Although the IIMs can affect patients of any age, including children, the peak age of onset is reported to be between 45 and 60 years. 1 Diagnostic delay is not uncommon in the IIMs. 6 Akin to many rheumatological/autoimmune-based diseases, the IIMs have a female predominance in the order of 2:1, 6 apart from inclusion body myositis, which is twice as common in men.…”

“…This could include examination of the breast, rectum, prostate and testes along with measurement of prostate-specific antigen. 1 Further imaging, including of the ovaries in women, and computerised tomography should be considered, as appropriate. Localising symptoms and signs should be investigated along standard lines.…”

Exacerbation of Murine Experimental Autoimmune Myositis by Toll‐Like Receptor 7/8

“…Idiopathic inflammatory myopathies (IIMs) are the largest group of myopathies (1). Various classifications have been proposed (2)(3)(4)(5). Myositis-specific autoantibodies are found, including antisynthetase antibodies, such as those specific for anti-histidyl-transfer RNA synthetase (anti-HisRS; also referred to as anti-Jo-1) (6)(7)(8).…”