Nodal B-cell lymphoma and Hodgkin lymphoma: current WHO classification and differential diagnostic dilemmas

Normal B cells undergo an apparently complex series of morphological phenotypic and molecular changes as part of their transformation from lymphoblasts to plasma cells. Understanding this pathway is the key to understanding the classification of lymphoma. The molecular changes underlying classical and nodular lymphocyte predominant Hodgkin lymphoma help us orientate these diseases with respect to normal B-cell development. This knowledge does not equate with a cellular origin for each tumour but helps us understand the relationship between morphology, phenotype, genotype and the clinical course of the disease. After the introduction of B-cell development, this article describes the nodal B-cell lymphomas, details the associated phenotype and genotype and documents the most important differential diagnoses.