Pathology of the skeletal muscles. a-d Rimmed vacuoles (RVs). Skeletal muscles show typical RVs on staining with HE (a) and modified Gomori trichrome (b). RVs are positive for p62 (c) and phosphorylated TDP-43 (d). e, f Intranuclear inclusions of the skeletal muscles. These inclusions were detectable only by electron microscopy (e). They had no obvious limiting membranes and were composed of straight filaments about 13–18 nm in diameter (f). a, b anterior tibial muscle, biopsy; c, d striated muscle of the esophagus, necropsy; e, f scalenus muscle, necropsy. Scale bar: a-d = 40 μm, e = 2 μm, f = 500 nm.