Idiopathic Inflammatory Myositis (Polymyositis and Dermatomyositis)

Idiopathic inflammatory myopathies (IIMs) are a heterogeneous group of rare and systemic autoimmune disorders characterized by various symptoms and mixed organ involvement, with muscle inflammation and proximal and symmetrical muscle weakness being the most common and representative. Skin, lungs, joints, and upper gastrointestinal tract may be affected as well. Along with signs and symptoms, myositis-specific and associated autoantibodies are crucial in the diagnostic process as they are associated with distinct clinical patterns and disease phenotypes. Occurrence in overlap with other connective tissue diseases and the association with malignancies are possible in IIM.