MYBL1 and diffuse astrocytoma: Histologically, diffuse astrocytoma, MYB- or MYBL1-altered typically shows low-to-moderate cellularity and is composed of well-differentiated neoplastic astrocytes with small, round-to-ovoid nuclei, diffusely permeating neuropil (Chiang et al., 2019; Wefers et al., 2020).