Fig. 2

Histological findings. The tumor showed circumscribed borders with focal areas of irregular tumor-brain interface, suggestive of brain invasion (inset, higher magnification), and tumor nests extending along the Virchow-Robin spaces (a). The hypercellular spindle areas appeared as short irregular fascicles of elongated cells, immersed in a dense collagenous stroma (b). The hypercellular epithelioid areas showed a predominant lobular architecture (c). In other adjacent areas, epithelioid cells were organized in sheet-like and cord-like structures, with clearer cytoplasm and multiple necrotic foci (d). The hypocellular areas were composed of a myxoid stroma with immersed spindle or stellate cells (e), often showing an angiocentric arrangement (f). In some myxoid areas there were more evident cytologic atypia and numerous daisy-like multinucleated elements (indicated by arrows), characterized by intracytoplasmic eosinophilic globules encircled by multiple nuclei (g). A rich vascular component was diffusely present, prevalently composed of small thin-walled vessels (h), and focally of larger vessels with thickened walls (i)