Clinicopathological analysis of primary intestinal diffuse large B-cell lymphoma: Prognostic evaluation of CD5, PD-L1, and Epstein-Barr virus on tumor cells

Background: Primary intestinal diffuse large B-cell lymphoma (iDLBCL) is rare. In this study, we investigated the clinicopathological features of this disease to further understand the prognostic value of CD5, programmed cell death ligand 1 (PD-L1), and Epstein-Barr virus (EBV) on tumor cells. Methods: Tumor specimens from 62 patients consecutively diagnosed with primary iDLBCL at a single institution were analyzed. Results: Our series consisted of EBV-positive (EBV ⁺ ) iDLBCL (n = 10), de novo CD5 ⁺ iDLBCL (n = 4), and DLBCL, not otherwise specified (DLBCL-NOS; n = 48). Notably, seven of 10 EBV ⁺ cases had treated lymphoma-associated (n = 4) or iatrogenic immunodeficiency (n = 3). Two of 10 EBV ⁺ cases expressed PD-L1 on tumor cells, whereas the remaining eight were positive for PD-L1 on microenvironment immune cells. Only one DLBCL-NOS case had neoplastic PD-L1 expression with a giant cell-rich appearance. Both EBV-harboring and PD-L1 expression on tumor cells, but not CD5, were associated with worse overall survival (OS) in iDLBCL patients receiving rituximab-containing chemotherapy (P = 0.0354, P = 0.0092, and P = 0.1097, respectively). Multivariate analysis identified PD-L1 positivity on tumor cells (P = 0.0106), PD-L1 negativity on microenvironment immune cells (P = 0.0193), and EBV positivity (P = 0.0324) as poor independent prognostic factors for OS. Among iDLBCL cases without any EBV association, CD5 positivity, or neoplastic PD-L1 expression, high PD-L1 expression (≥40%) on microenvironment immune cells predicted an extremely favorable outcome. Conclusion: EBV ⁺ iDLBCL mainly comprised immunodeficiency-associated patients, which may highlight the specificity of the intestine. PD-L1 expression on tumor cells or microenvironment immune cells was found to have an opposite prognostic impact in iDLBCL.