Biological characterization of nodal versus extranodal presentation of diffuse large B-Cell lymphoma using immunohistochemistry.

Introduction: Diffuse large B cell lymphoma (DLBCL) of primary nodal (PN) or primary extranodal (PEN) origin may differ immunophenotypically, in that PEN lymphoma cells may originate from activated rather than germinal center B (GCB) cells. We evaluated the relationship between DLBCL clinicopathological features, including expression of B-cell differentiation markers, and primary tumor site.

Patients And Methods: Expression of CD10, Bcl-6, Bcl-2, and MUM1 was determined in paraffin-embedded tissues from 123 patients with DLBCL.

Results: Of the 123 patients with DLBCL, 40 (32.5%) had the GCB and 83 (67.5%) had the non-GCB phenotype. Fifty-one patients (42%) showed disease involvement at PEN sites, including 29 with disease in the gastrointestinal (GI) tract (14 in the stomach, 15 in the intestine). Of these 51 patients, 16 (31.4%) were classified with the GCB and 35 (68.5%) with the non-GCB subtype. There were no differences in the frequencies of GCB and non-GCB subtypes among primary sites. Of the 72 patients with PN DLBCL, 22 (31%) had the GCB and 50 (69%) had the non-GCB subtype. There were no differences in the frequencies of GCB and non-GCB subtypes between patients with PN and PEN DLBCL. Although lactate dehydrogenase (LDH) concentration > normal, stage >II, and rituximab-cyclophosphamide, doxorubicin, vincristine, and prednisone (RCHOP) treatment were independent predictors of overall survival (OS), GCB subtype, and presence of PEN disease failed to predict survival upon multivariate analysis.

Conclusion: There was no difference in GCB and non-GCB phenotypes between patients with PN and PEN DLBCLs. Additional studies are needed to further assess molecular differences between the two groups.