In the first part of the paper, we describe details of this landscape and their biological meanings in terms of subtype-specific transcriptomic portraits for DLBCL, BL and FL as well as for rarer entities such as aggressive lymphoma with simultaneous rearrangements of MYC and BCL2 (so called “double hit lymphomas”; DHL), IRF4-rearranged large cell lymphoma (IRF4-LCL), and MYC-negative high grade B-cell lymphomas (formerly called Burkitt-like lymphomas) with 11q aberration pattern (mnBLL-11q). The gene discussed is IRF4; the disease is diffuse large B-cell lymphoma.