B-Cell lymphomagenesis in Non-Hodgkin lymphomas: Subtypes according to their cell of origin (Part 2)

Abstract

Non-Hodgkin lymphomas (NHL) derived from B cells represent a heterogenous group of neoplasms originated at different stages of the B cell development. The germinal center (GC) of lymphoid follicles is a key microenvironment where B cells experiment somatic hypermutation and immunoglobulin class switching. Alterations in these processes may lead to lymphomagenesis. Thus, contemporary classification of NHL puts special emphasis on cell origin and differentiation profile for B cells of the germinal center or post-germinal center. In clinical, molecular and histopathological terms, lymphomas derived from the GC include entities such as follicular lymphomas (FL) and diffuse large B-cell lymphomas (DLBCL) that are characterized by alterations in regulatory genes in the GC response (e.g. BCL2, BCL6, EZH2). The understanding of these pathogenic pathways has allowed the refinement of classification, prognosis and therapeutic alternatives, particularly with the rise of targeted therapies and immunotherapies. In this second section on B-cell lymphomagenesis, we will address several of the most frequent lymphoma subtypes within each category of the cell-of-origin–based classification of B-cell neoplasms such as chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL), FL, mantle cell lymphoma (MCL), and Burkitt lymphoma (BL). A subsequent article will complete the overview by covering other common entities, including DLBCL, mucosa-assisted lymphoid tissue (MALT) lymphoma, and lymphoplasmacytic lymphoma (LPL).