Fig 4.

Trichrome stain (A) demonstrates the presence of an enlarged perivascular space (white arrow, glia limitans; black arrow, inner pial membrane; black arrowhead, vessel lined by outer pial membrane; curved arrow, perivascular space). Multiple such lesions were seen in the surgical specimen. Glial fibrillary acidic protein stain (B) and CD68 stain (C) demonstrate reactive astrocytes (arrows in B) and perivascular microglia (arrows in C) as multiple brown-staining dots, confirming chronicity of the pathophysiologic process. Luxol fast blue stain (D) demonstrates diffuse absence of blue staining (myelin staining), indicating demyelination and gliosis in the brain parenchyma surrounding the dilated perivascular space (magnification of all slides, 20×).