Progressive myopathies characterized by the presence of inclusion bodies on muscle biopsy. sporadic and hereditary forms have been described. the sporadic form is an acquired, adult-onset inflammatory vacuolar myopathy affecting proximal and distal muscles. familial forms usually begin in childhood and lack inflammatory changes. both forms feature intracytoplasmic and intranuclear inclusions in muscle tissue. (adams et al., principles of neurology, 6th ed, pp1409-10)

Inclusion body myositis (IBM) () (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 (located on or close to the torso) and distal muscles (close to hands or feet), most apparent in the finger flexors and knee extensors...