Figure 1

Light and electron microscopy demonstrating vasculitic neuropathy. Representative photomicrographs of fixed sections obtained from the left superficial radial nerve biopsy are shown. Hematoxylin and eosin (H&E)-stained sections demonstrate severe axonal loss with almost complete depopulation of myelinated axons in a nerve fascicle (black arrow), (A) supported by the lack of neurofilament (NF) staining (black arrow) on immunohistochemistry (IHC), as shown in (B). H&E-stained sections show focal vasculitis involving small vessels with transmural lymphocytic infiltration in the epineurium (black arrow), (C), verified by CD45 (also known as leukocyte common antigen)-positive mononuclear cell infiltrates on IHC (black arrow), (D). Electron micrographs further demonstrate the severe axonal loss (~90 to 95% of large and small myelinated axons are no longer present) with residual myelinated axons (black arrows) and ongoing Wallerian degeneration (dark blue arrows) seen at lower (E) and higher magnifications (F). Original magnifications: A and B: 20×, C and D: 64×, E: 1000× and F: 5000×.