The revised who classification of lymphomas – what has changed for the pathologist and clinician

Abstract

The latest revision of the WHO classification reflects new insights gained over the preceding 8 years. The revision illuminates a broader spectrum of lesions at the very early stages of lymphomagenesis, providing guidance for diagnosis and management. These include monoclonal B-lymphocytosis, in situ follicular and mantle cell neoplasias, and pediatric type follicular lymphoma. Criteria have been developed for the distinction of lymphoplasmacytic lymphoma and marginal zone lymphoma, in part relying on identification of mutations in MYD88. There is a broader understanding of the genetic heterogeneity of DLBCL, and the distinction of the ABC and GCB subtypes. Moreover, aggressive B-cell lymphomas with double/triple hit involving BCL2, BCL6 and MYC are newly segregated from other DLBCL. In addition, newly recognised entities include IRF4-rearranged large B-cell lymphoma, with Burkitt-like lymphoma with 11q aberrations. Changes to the classification of T-cell lymphomas will be further clarified in a separate lecture.