Diffuse large B cell lymphoma: Variants, subgroups and subtypes/entities

Diffuse large B-cell lymphoma (DLBCL) is the most common type of lymphoma worldwide, and represents a clinically, pathologically and biologicaly very heterogeneous group of tumours. Recent studies have subdivided diffuse large B cell lymphomas into morphological variants, molecular and immunophenotypical subgroups and distinct entities. An immunophenotypical subdivision of DLBCL, into germinal centre-like (GCB) and non-germinal centre-like (non-GCB) subgroups, using a combination of antibodies to CD10, BCL6 and MUM1, does not correlate exactly with gene expression profile of GCB and activated peripheral B-cells (ABC). Some studies reported that combination of CD10, BCL6 and MUM1 expression could subdivide DLBCL patients into long- and short-time survivors. The WHO classification of 2008. recognizes a group of aggressive B-cell lymphomas that are not readily classified as either Burkitt lymphoma (BL) or DLBCL, and provisional category of B-cell neoplasms with features intermediate between DLBCL and classical Hodgkin lymphoma. Furthermore, the new classification recognizes the patient age, site-specific categories, and clinical factors in defining variants of DLBCL. The WHO classification of 2008. is the result of successful international collaboration among pathologists, biologists and clinicians, but heterogeneous group of DLBCL will be the subject of further investigation.