The immunohistochemistry of neurofibroma or pNF includes extensive but not diffuse S100 positivity in the Schwannian component and SOX10 positivity; a lattice-like CD34+ fibroblastic network; a less than 3% Ki67 labeling index; diffusely enlarged nerves that need to be replaced, often involving multiple nerve fascicles; and EMA+ perineurial cells 16. The gene discussed is SOX10; the disease is neurofibroma.