Abstract

Diffuse large B-cell lymphoma is the most common lymphoma worldwide. Both morphologically and prognostically it represents a diverse spectrum of disease. Traditional morphologic subclassification often results in poor interobserver reproducibility and has not been particularly helpful in predicting outcome. Recent gene expression profiling studies have classified diffuse large B-cell lymphoma into 2 main subtypes, germinal center B-cell and activated B-cell, with the germinal center type showing an overall better survival. Validation of these subtypes has become possible for the practicing pathologist with the use of surrogate immunohistochemical markers. Importantly however, these prognostic studies were performed on material from the pre-rituximab treatment era. With the now well-accepted addition of rituximab (anti-CD20 antibody) to the typical large B-cell lymphoma chemotherapeutic regimen, a revalidation of any survival differences between the large B-cell lymphoma subgroups is necessary. This short review covers the current clinical, morphologic, immunophenotypic, genetic, gene expression profiling, and prognostic (studies before and after the addition of rituximab) features of de novo diffuse large B-cell lymphoma.