Inclusion body myositis (IBM) was first identified as a specific disorder about 40 years ago and is now recognized to be the most frequently presenting primary myopathy in middle age and beyond. Initial characterization was based on the observation of specific pathological features distinguishing it from polymyositis. It was soon appreciated that there were also distinguishing clinical features...

Inclusion body myositis (IBM) is a progressive inflammatory skeletal muscle disease of unknown cause and without effective treatment. This article discusses existing literature, emphasizing disease mechanisms and models. In particular, it addresses limitations in the beta-amyloid-mediated theory of IBM myofiber injury, flawed rationales of animal models of this disease, and recent reports regar...