Figure 1.

Illustrative cases of malignant transformation of diffuse astrocytoma. (a) Preoperative T1 weighted postcontrast magnetic resonance imaging showing left frontal mass. (b) H and E stain showing moderate cellularity with nuclear atypia of astrocytes. (c) T1 weighted postcontrast magnetic resonance imaging at 4 months later showing progressive left frontal mass with corpus callosum involvement. (d) H and E stain showing an anaplastic transformation, including astrocytes with pleomorphism. (e) T1 weighted postcontrast magnetic resonance imaging at 8 months later showing left frontal tumor crossing to the right side. (f) H and E stain showing glioblastoma features, including hypercellularity of astrocytes and endothelial proliferation (arrow)