Neuropathological results. In the astrocytoma WHO grade II (A II°, left row) density and pleomorphy of the tumor cells are low to moderately pronounced. Tumor cells express GFAP, MAP2c, WT1 and mutated IDH1 (R132H). A subpopulation of ca. 1-2% shows a nuclear accumulation of p53. The glioblastoma multiforme WHO grade IV (GB IV°) has a markedly increased density and pleomorphy, combined with an increased mitotic and proliferative activity, necrotic areas and microvascular proliferations. Compared to the primary astrocytoma, GFAP expression is present only in a subpopulation of tumor cells (ca. 65%) whereas nuclear accumulation of p53 occurs in more tumor cells (5-10%). In the relapsed glioblastoma (rGB IV°) the percentage of tumor cells expressing GFAP (ca. 30%) and WT1 (ca. 10%) decreases. Both, the epidural (emetGB IV°) as well as the pulmonal (pmetGB IV°) metastasis demonstrate expression of GFAP in 10-20% and of WT1 only in small groups and single tumor cells (<10%). Bars = 50 μm, corresponding to a magnification ×200.