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

Abstract

The idiopathic inflammatory myopathies are a group of conditions characterised by inflammation 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 inflammatory myopathy, based on up-to-date knowledge. The recently updated classification criteria and treatment options will also be described.

Keywords: Dermatomyositis; idiopathic inflammatory myopathies; inclusion body myositis; myositis; polymyositis.

Fig 1.

Gottron’s papules over metacarpophalangeal and interphalangeal joints in a patient with dermatomyositis. Reproduced with permission from Dugan et al.

Fig 2.

Heliotrope rash over the left eyelid with associated periorbital oedema. Reproduced with permission from Dugan et al.

Fig 3.

Mechanic’s hands: scaling, cracking and fissuring with bleeding along the lateral and palmar aspects of the fingers. Reproduced with permission from Dugan et al.