MKI67 and diffuse astrocytoma: IDH-mutated diffuse astrocytomas (WHO grade II) with low cellularity had only a few scattered Ki-67 positive tumor cells and moderate expression of exclusion-marker (Fig. 1A), whereas IDH-mutated anaplastic astrocytomas (WHO grade III) with moderate cellularity showed moderate expression of the exclusion-marker (Fig. 1B).