[Molecular and histological features of diffuse large B-cell lymphoma]

Diffuse large B-cell lymphoma (DLBCL) is a high-grade lymphoproliferative disease of mature B cells, representing the most common lymphoid malignancy of adulthood. There are multiple distinct subgroups of DLBCL in the 2008 WHO classification, organ specific forms, DLBCL associated with immunodeficiency and viral infections and rare CD20 negative and intermediate forms. However, most of the cases are still classified under the DLBCL not otherwise specified (NOS) category. This group of disease shows remarkable heterogeneity with respect to clinical presentation, biology and response to treatment, reflecting several molecular subgroups: the origin of B cells at various developmental stages, the oncogenic pathways that drive tumor development and also epigenetic changes and mutations involving the escape of immune surveillance. Contemporary chemo-immunotherapy does not result in durable remissions in as many as 30% of the cases. To achieve longer survival, the definition of new biomarkers are needed for targeted therapy based on better subgrouping of tumors according to the molecular pathways involved in lymphomagenesis. This paper summarizes the most important features influencing the outcome of this broad disease at the level of morphology, phenotype and genotype and gives a guideline for the routine pathological practice at present for the diagnostics of DLBCL treated by chemo-immunotherapy.