Fig. 2

Intraoperative view and its illustration, histological examination, and postoperative MR imaging in Case1. a Surgical view shows a tumor tightly adherent to the inferior part of the vein of Galen (white arrow) T , tumor. b Intraoperative illustration of the microanatomical relationship between the tumor origin and arachnoid membranes from the perspective of the lower side of the vein of Galen (black bold arrow tumor attachment, 1 splenium, 2 vein of Galen, 3 straight sinus, 4 cerebellum, 5 pineal gland, 6 quadrigeminal plate). c Histological examination shows transitional meningioma (hematoxylin and eosin stain, scale bar, 100 μm). d MRI at 1 month postoperatively shows gross total removal of the tumor mass