diffuse large cell lymphoma (DLCL) includes centroblastic lymphoma, B-cell immunoblastic lymphoma and B-cell large cell anaplastic lymphoma in the Kiel classification; this neoplasia may present as a de novo condition or it may derive from the transformation of follicle centre cell lymphoma or, less frequently, of marginal zone lymphoma

the tumor cells are pan-B+ and CD45+; CD5 and CD10 are positive in a minority of cases; positivity for surface Ig is found in the majority of cases, a minority of which also show intracytoplasmic Ig; some cases of the anaplastic subtype may be CD30+; usually, BCL6 is positive in cases with predominant centroblastic morphology, whereas syndecan-1 (CD138) tests positive in the immunoblastic variant; the putative normal cellular counterparts are cells of follicle / post follicle centre origin that have encountered the antigen and harbour somatic hypermutations of the Ig-gene variable region

the cells are large, with vesicular nuclei at least twice the size of the nucleus of a small lymphocyte; there is a mixture of cells resembling centroblasts and immunoblasts; in rarer cases the cells are morphologically indistinguishable from those seen in anaplastic lymphoma of T- or null cell type

the large majority of cases show clonal cytogenetic lesions; some of these changes are associated with a known primary genetic defect responsible for lymphomagenesis, whereas a plethora of additional changes may be involved in tumor progression.
most studies failed to establish the prognostic predictivity for any primary chromosome defect, whereas there is evidence that several secondary aberrations may affect prognosis.