The immunophenotypic profile of gastric diffuse large B-cell lymphomas (DLBCL) is similar to those seen in other sites. They express CD45 and pan B-cell markers such as CD20, CD22, CD79a, and PAX-5. Monotypic immunoglobulin (surface or cytoplasmic) is variably present. Other positive markers include CD10, BCL6 (shown here), and BCL2. In gastric DLBCL, the rearrangement of BCL6 gene is more common and the rearrangement of BCL2 gene is less common as compared to nodal DLBCL. CD5 is present in about 10% of cases. A small number of cases show post-germinal center or plasma cell-associated markers such as CD38, VS38, and MUM1. Ki-67 labeling index is high (>20%). A minority of cases express CD30. Pan-T markers are negative.