Fig. 2

Histological features of angiomatous pleomorphic xanthoastrocytoma. a–d The entire neoplasm is invested with an abundant vascular meshwork consisting of a sinusoidal configuration and venous malformation. e, f The tumor is composed of neoplastic astrocytes surrounded by a poorly canalized configuration. g, h Foci of abnormal veins of varying size are observed within the tumor. The blood vessel walls are of variable thickness and some show hyaline degeneration; others are large, thin-walled vessels with irregular lumens. i Foci of hemosiderin are present within the tumor. j Focal fibrinoid necrosis, hyalinization, and a moderate infiltration of lymphocytes and plasma cells are observed in the vessel wall. k A desmoplastic reaction caused by plasma proteins that have exuded through the leaky walls of newly formed blood vessels. l The pleomorphic histology of the tumors includes a varying cell density mainly consisting of cells with significant nuclear and cellular pleomorphism. The corresponding histological features are indicated by arrows