The inflammation is typically most prominent early and may be minimal at later time points. Most of the cells are activated T cells. Familial forms of the disease often lack inflammation altogether and are therefore sometimes referred to as inclusion body myopathies. Grouped angulated atrophic fibers are frequently present, although their presence does not necessarily imply denervation. In the paraffin sections the vacuoles appear near empty.
Frozen sections are necessary for identifying rimmed vacuoles containing small basophilic granules.
Interestingly, a variety of antigens more commonly associated with neurodegenerative diseases can be demonstrated within the vacuoles. Sporadic, but not hereditary, cases may react with antibodies to phosphorylated tau.1 Ultrastructural examination shows characteristic twisted tubulofilaments, amyloid-like fibrils, and membranous whorls, although the latter may predominate. References Carpenter S. Inclusion body myositis. J Neuropathol Exp Neurol . Curr Opin Neurol .