Vigorously proliferating B220+CD19+IgM+ BAL17CNS cells expressing Myc derived from BAL17 lymphoma cells by repeated isolation and re-transplantation into the CNS [75] disseminate in the CNS in a topographical manner similar to that of human PCNSL with preferential growth in the ventricular system, the adjacent basal ganglia, and hemispheric white and grey matter; they also exhibit the characteristic angiotropism (Figure 5a–f) [75]. The gene discussed is CD40LG; the disease is lymphoma.