摘要：

Diffuse large B-(DLBCL) of the gastrointestinal tract is heterogeneous, including mucosa-associated lymphoid tissue (MALT) origin and non-MALT, and they are indistinguishable. MALT is a of a post-germinal center (GC) B-origin, which is negative for expression in low-grade but may become positive in high-grade . Because expression patterns in of GC and non--origins have recently been characterized and CD10 is generally regarded as a specific marker for , we critically evaluated gastric and small intestinal DLBCLs to see whether it is possible to identify of -origin by immunostaining in archival specimens. High-grade MALT (H-ML) of the stomach (n = 20) was defined by the presence of a concomitant lymphoepithelial lesion and/or follicular colonization; and DLBCLs de novo, both gastric (n = 31) and intestinal (n = 21), were defined by the absence of the above features. Immunostaining for and CD10 was done using -fixed, paraffin-embedded sections and was examined independently by three pathologists. Staining for was positive (>10% of ) in 55 of 72 cases. However, two distinct patterns were recognized among those positive: diffusely dense (>75%) and sporadic (<75%). The former was further characterized by a consistency of + density at any given area, resembling the staining pattern of the GC or (FL) (GC/FL pattern), whereas the latter was, besides less dense population, by variable density from area to area. The GC/FL pattern was observed in 36% and 38% of gastric and intestinal DLBCLs de novo, respectively, but in none of the gastric H-ML. CD10 was positive in 12 of 71 cases (17%), all coexpressing . CD10+ were more frequent in the intestinal (33%) than in gastric DLBCLs ( approximately 15%). Significantly, CD10 expression was observed in three gastric H-MLs, including one that displayed a distinct lymphoepithelial lesion.1). showing a diffusely dense pattern of expression should be distinguished from those showing a sporadic pattern; for the former most likely represents the of -derivation, and the latter non-GC, including MALT ; 2). of -origin thus defined accounted for about one third of gastric as well as intestinal DLBCLs de novo but none of the gastric H-ML; and 3). CD10 expression can be seen in MALT and should not be used as the marker for .

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