Neuropathological profiles of the patients in the clinical progressive muscular atrophy group. (A–J) correspond to patient 2. The corticospinal tracts (CST) did not display myelin pallor (A), loss of large axonal fibres (B), or aggregation of macrophages (C). Additionally, in the primary motor cortex, neither the loss of Betz cells (D) nor aggregation of macrophages (E) was detected. The upper layers of the primary motor cortex rarely contained phosphorylated 43 kDa TAR DNA-binding protein (pTDP-43)-positive neuronal (F) and glial (G) inclusions. The spinal anterior horn displayed severe neuronal loss (H), pTDP-43-positive skein-like inclusions (I) and Bunina bodies (J). (K–M) correspond to patient 12. The CST displayed myelin pallor (K) and the depletion of large axonal fibres (L). Neuronophagia was often found in the primary motor cortex (M, arrows). (N and O) correspond to patient 6. The spinal motor neurons contained basophilic inclusion bodies (N) that were positive for antifused-in-sarcoma (FUS) based on immunohistochemistry (O). (A and K) Klüver-Barrera staining, (B) antiphosphorylated neurofilament immunohistochemistry, (C and E) anti-CD68 immunohistochemistry, (D, H, J and M) H&E staining, (F, G and I) anti-pTDP-43 immunohistochemistry and (O) anti-FUS immunohistochemistry. Scale bars: (A and K) 3 mm, (D and E) 100 μm, (C, H and M) 50 μm, (B) 20 μm and (F, G, I, J, N and O) 10 μm.