Inflammatory myopathies and overlap syndromes: Update on histological and serological profile.

The term 'inflammatory myopathies' (IMs) comprise a group of muscle diseases formed by four main categories known as polymyositis (PM), dermatomyositis (DM), inclusion body myositis (IBM) and immune-mediated necrotizing myopathy (IMNM). Due to the increasing evidence of IMs over the course of different autoimmune diseases, the overlap myositis (OM) has been recently recognized as a possible stand-alone entity. IMs are characterized by a wide spectrum of autoantibodies, and the panel of myositis-associated autoantibodies (MAA) has dramatically increased over the last years giving the clinicians a further crucial support to differentiate the different types of myositis. This study aims to collect the most relevant evidence published up to date on the most commonly described OM with a particular emphasis on their histological aspects and also serological features.