Inclusion body myositis (IBM) (/maɪoʊˈsaɪtɪs/) (sometimes called sporadic inclusion body myositis, sIBM) is the most common inflammatory muscle disease in older adults. The disease is characterized by slowly progressive weakness and wasting of both proximal muscles (closest to the body's midline) and distal muscles (the limbs), most apparent in the finger flexors and knee extensors. IBM is often confused with an entirely different class of diseases, called hereditary inclusion body myopathies (hIBM). The "M" in hIBM is an abbreviation for "myopathy" while the "M" in IBM is an abbreviation for "myositis". These diseases should not be confused with each other. In IBM, two processes appear to occur in the muscles in parallel, one autoimmune and the other degenerative. Inflammation is evident