TNF and myeloid sarcoma: Applying immunohistochemistry for CD3, TNF, and GFAP (glial fibrillary acidic protein) to show the PVS border, we repeated this finding, as the proportion of T cells located in the parenchyma was significantly higher in MS active and mixed active/inactive lesional compared to inactive lesional and normal-appearing WM (Figures 6E and 6F).