SOAT1 and primary central nervous system lymphoma: Regardless of clonal selection or clonal evolution, recurrent lymphoma cells have undergone genetic and epigenetic changes in which activation of the B cell receptor (BCR) and Toll-like receptor (TLR) pathways, Janus kinase/signal transducers and activators of transcription (JAK/STAT), and immune escape are the key mechanisms of PCNSL; these alterations are the targets of new therapies.