Figure 2

Pathological findings of meningioangiomatosis (MA). (A) The cortical component of the lesion shows prominent small blood vessels surrounded by perivascular meningothelial cell proliferation, which is the characteristic morphology of MA (hematoxylin-eosin, HE; ×100). (B) Dilated perivascular spaces and cysts are present within the perivascular cell cuffs (HE, ×100). (C) Cord-like nests of hyperplastic spindle cells are seen perpendicular to the surface of the cerebral cortex, where encephalocele and leptomeningeal cell proliferation are present. Hyalinized collagen fibers appear as concentrically arranged acellular eosinophilic lamellae within areas of reactive gliosis (HE, ×100). (D) The perivascular cells and cystic walls are focally positive for smooth muscle actin (immunohistochemistry, IHC; ×100). (E) The perivascular cells and cystic walls are positive for D2-40 (IHC, ×200). (F) The perivascular cells are negative for H-cald (IHC, ×200).