Inclusion Body Myositis

Abstract

This article highlights the clinical and diagnostic features of inclusion body myositis (IBM) and provides recent insights into the pathomechanisms and therapeutic strategies of the disease. IBM is an often-misdiagnosed myopathy subtype. Due to the insidious onset and slow progression of muscle weakness, it can often be dismissed as a sign of aging as it commonly presents in older adults. While challenging to recognize upon initial clinical evaluation, the recent recognition of specialized stains highlighting features seen on muscle pathology, the use of diagnostic tools such as the anti-cytosolic 5'-nucleotidase 1A antibody biomarker, and the ability of muscle imaging to detect patterns of preferential muscle involvement seen in IBM has allowed for earlier diagnosis of the disease than was previously possible. While the pathogenesis of IBM has historically been poorly understood, several ongoing studies point toward mechanisms of autophagy and highly differentiated cytotoxic T cells that are postulated to be pathogenic in IBM. Overall advancements in our understanding of IBM have resulted in improvements in the management of the disease and are the foundation of several strategies for current and upcoming novel therapeutic drug trials in IBM.