Vol 1, No 1 (2010)
Review paper
Published online: 2010-02-04
The WHO (2008) classification of B-cell lymphomas - basics and important changes
Hematologia 2010;1(1):1-14.
Abstract
In 2008, the World Health Organization published a revised and updated edition of the
classification of lymphoid tissues tumors. Within the category of indolent B-cell lymphomas
there appeared new definitions and diagnostic criteria for established diseases such as chronic
lymphocytic leukemia and Waldenstöm’s macroglobulinemia. New provisional entities were
introduced such as splenic B-cell lymphoma/leukemia, unclassifiable, splenic diffuse red pulp
small B-cell lymphoma and hairy cell leukemia - variant. Clinically different pediatric
follicular lymphoma and pediatric nodal marginal zone lymphoma have been singled out.
”Early” lymphoid proliferations with still undetermined clinical significance have been described
such as monoclonal B-cell lymphocytosis, follicular and mantle cell lymphoma in situ.
Diversity of morphological, biological and clinical features of diffuse large B-cell lymphoma
(DLBCL) has served as basis to division into variants, subgroups, subtypes and clinico-pathological entities. Morphological variants, molecular subgroups based on gene-expression
profiling (germinal center B-cell like and activated B-cell like) and immunohistochemical
subgroups of DLBCL were included into an entity called DLBCL, not otherwise specified. New
distinct DLBCL subtypes based on topography were defined to include primary DLBCL of the
CNS and primary cutaneous DLBCL, leg type. The importance the role of Ebstein-Barr virus
(EBV), human herpesvirus 8 (HHV-8) and immunodeficiency status in DLBCL pathogenesis
served as basis for introduction of new clinico-pathological entities such as EBV positive
DLBCL of the elderly, DLBCL associated with chronic inflammation and large B-cell lymphoma
arising in HHV8-associated multicentric Castleman disease. Two new large B-cell
lymphomas with features of DLBCL overlap with Burkitt lymphoma or classical Hodgkin
lymphoma have been introduced.
Keywords: 2008 WHO classificationB-cell lymphomas