Histologically, sIBM is characterized by chronic myopathic features, lymphocytic infiltrates invading non-vacuolated fibers, vacuolar degeneration, and accumulation of amyloid-related proteins.

When compared with the normal cricopharyngeus muscle, the muscle from patient with Zenker's demonstrates fiber dropout (due to necrosis, as evidenced by scattered degenerative fibers), greater ...

Muscle fibers do not normally express MHC class I antigens. In sIBM, however, MHC class I is ubiquitously expressed even on muscle fibers remote from the inflammation (Figure 1D). [4, 28] In other ...