Diffuse large B cell lymphomas (DLBCL) are aggressive B-cell lymphomas that are clinically, pathologically and genetically diverse, in part reflecting the functional diversity of the B-cell system. The focus in recent years has been towards incorporation of clinical features, morphology, immunohistochemistry and ever evolving genetic data into the classification scheme. The 2008 WHO classification reflects this complexity with the addition of several new entities and variants. The discovery of distinct subtypes by gene expression profiling (GEP) heralded a new era with a focus on pathways of transformation as well as a promise of more targeted therapies, directed at specific pathways. Some DLBCLs exhibit unique clinical characteristics with a predilection for specific anatomic sites; the anatomic site often reflects underlying biological distinctions. Recently, the spectrum of EBV-driven B-cell proliferations in patients without iatrogenic or congenital immunosuppression has been better characterized; most of these occur in patients of advanced age, and include EBV-positive large B-cell lymphoma of the elderly. HHV-8 is involved in the pathogenesis of primary effusion lymphoma, which can present as a “solid variant.” Two borderline categories were created; one deals with tumors at the interface between classical Hodgkin lymphoma (cHL) and DLBCL. The second confronts the interface between Burkitt Lymphoma (BL) and DLBCL, so called “B-cell lymphoma, unclassifiable, with features intermediate between diffuse large B-cell lymphoma (DLBCL) and Burkitt lymphoma” in the 2008 classification. Most cases harbor both MYC and BCL2 translocations, and are highly aggressive. Another interesting entity is ALK+ DLBCL, which renders itself potentially targetable by ALK inhibitors. Ongoing investigations at the genomic level, with both exome and whole genome sequencing, are sure to reveal new pathways of transformation in the future.