Muscle fibers in OPMD patients show a variety of changes. One significant alteration is the presence of [rimmed vacuoles](href="") within the muscle cells. These vacuoles are often surrounded by granular material and can be highlighted using special stains such as modified Gomori trichrome. Additionally, there is evidence of muscle fiber atrophy, particularly in type II fibers, and increased variability in fiber size, a phenomenon referred to as fiber type grouping.
