The diversity of diffuse large B-cell lymphoma in extranodal sites: overview and update

Extranodal lymphomas are a diverse group of low and high grade neoplasms of B-, T-, and NK-cell lineage, each with characteristic sites of origin, morphology, immunophenotype, genetic features, patterns of spread, and prognosis. The diversity is sometimes seen even within a single histologic type of lymphoma. This phenomenon is especially striking in the category of diffuse large B-cell lymphoma (DLBCL). DLBCLs as classified in the WHO Classification are clinically and pathologically heterogeneous (Swerdlow et al. 2008; Stein et al. 2008). Since the publication of the most recent edition of the WHO Classification of tumours of haematopoietic and lymphoid tissues (Swerdlow et al. 2008), a number of advances in the understanding of these lymphomas have been made. This review provides an overview of extranodal DLBCLs and describes recent updates regarding these lymphomas.