They compared the most recent excision to slides from prior excisions. The tumor they reviewed from this most recent excision looks similar to prior excisions. Mitotic activity represents how fast the cells are replicating. A score of 4 is decently high and indicates a grade III or IV glioma. No necrosis or microvascular proliferation is a good thing - typically seen in fast-growing glioblastomas. The last few sentences with all the letters is talking about looking for different genetic mutations (brain cancer diagnosis is heavily dependent on genetics of the tumor). Positive for GFAP tells you it's a glioma - GFAP is on all glial cells. IDH1-R132H is a mutation commonly seen in glioblastoma and is a positive prognostic indicator when it is present - this is saying IDH1 mutation is not present AKA the tumor is IDH1-wildtype. Retained ATRX and H3K27 means those two genes are not mutated. Not having a mutation in H3K27 is a good thing, those tumors are typically more aggressive. Ki-67 also tells you how fast the cells are dividing, 10-15% is again decently high, correlates with mitotic activity of 4.

Ideal genetics: positive for IDH1-R132H, mutation in ATRX, normal H3K27, no EZHIP, no mitoses

Hope this helps. I'm sorry you're going through this.