IDH2 and oligodendroglioma: In 13/22 (59.1%) IDH-mutant/1p19q-codel oligodendrogliomas, tumor cells expressed NG2/CSPG4, either focally or diffusely, with a slight prevalence in grade III tumors (6/8, 75%) compared to grade II tumors (7/14, 50%) (Table 1) (Figure 1A,B), mainly in infiltration areas.