[Gastric lymphoma: still an interdisciplinary challenge].

Differentiation of chronic gastritis from marginal zone B-cell lymphoma (MZoL) of MALT type is often difficult for the pathologist. Diagnostic tools include CD20 stain to highlight lymphoepithelial lesions, Wotherspoon grading of the infiltrate, and clonality analysis of the B-cells. MZoL may partially transform into a diffuse, large B-cell lymphoma, which the authors have named blastic MZoL. Blastic MZoL may be present with or without small cell MZoL. Without this component, blastic MzoL, while being CD10-negative, is presently difficult to positively diagnose since specific immune markers are still lacking. Blastic MZoL has a very favourable outcome compared to conventional diffuse large B-cell lymphomas (DLBCL). Moreover, there are conventional DLBCL in the stomach, mostly in a setting of a secondary organ involvement. The biology of these gastric DLBCL is identical to their extragastric counterparts. This is also true for primary gastric Burkitt lymphoma and mucosal involvement in B-CLL or mantle cell lymphoma. Unfavourable outcomes are always observed for EBV-triggered lymphoproliferations in immunodeficiency and peripheral T-cell lymphomas which might also arise or be initially diagnosed in the stomach.