Idiopathic inflammatory myopathies: a review

Idiopathic inflammatory myopathy (IIM) is the umbrella term including dermatomyositis (DM), polymyositis (PM), overlap myositis (OM), sporadic inclusion body (IBM) and necrotising autoimmune (NAM), also known as immune-mediated myopathy. There some debate to whether PM exists a discrete entity, or perhaps an overly generalising encompassing connective tissue disease associated myositis, OM, previously poorly recognised NAM. As such, will not be covered in detail this review. DM, OM NAM all present similarly, with proximal weakness elevated creatine kinase (CK) level. By contrast, IBM preferentially involves long finger flexors quadriceps, presents normal only mildly CK. Developments serological testing imaging are shifting diagnostic paradigm away from reliance on histopathology. The therapeutic armamentarium for IIM continues evolve, intravenous immunoglobulin rituximab proving successful refractory disease. This review provide algorithm clinician help distinguish between subtypes – emphasis clinical assessment, serology imaging, well discussion of options escalation immunotherapy.