Fig. 2

Histological findings of the 1st surgical specimen. Massive hemorrhage was observed within the tumor (a: HE stain, x 2). Two closed arteries circled by the blue dotted line were identified in the peri-tumoral abundant collagen regions (b: HE stain, x 2). High magnification of one of the closed arteries (c: HE stain, x 40). The tumor involved the choroid plexus (d: HE stain, x 10). This tumor is consistent with fibrous type meningioma composed of spindle-shaped tumor cells with a fascicular or storiform arrangement (e: HE stain, x 20). In addition, dilated abnormal vessels can be seen, of which the walls are thin and the internal elastic membrane appears fragile (f: Elastic-van Gieson stain, x 20)