Histologic and immunohistologic findings and prognosis of 40 cases of gastric large B-cell lymphoma

It has been considered that gastric large B cell lymphoma mainly consists o f mucosa-associated lymphoid tissue lymphoma (MALToma) with large cell tran sformation. However, debate continues about the cell lineage. We analyzed 6 1 operated cases of gastric B cell lymphoma, mainly focusing on 40 cases of diffuse large cell lymphoma (DLCL). Immunohistologically, two cases were c lassified as CD10-positive follicular lymphoma, 19 cases were low-grade MAL Toma, 11 CD10-negative DLCL with a component of low-grade MALToma (high-gra de MALToma), 12 CD10-positive DLCL, and 17 CD10-negative DLCL without MALTo ma (pure DLCL). Lymphoepithelial lesion (LEL) was found in all -cases of hi gh-grade MALToma, and in eight of these its invasion was confined to the mu cosa and submucosa. Expression of Bcl-6 was detected in two cases of high-g rade MALToma. Only two cases of CD10-positive DLCL had large cell LEL, and seven cases showed tumor invasion beyond the submucosa. All 12 cases were p ositive for Bcl-6, and a delicate meshwork of CD35 (Ber-MAC-DRC)-positive f ollicular dendritic cells was detected in eight cases. Pure DLCL of all 17 cases reached the proper muscle layer or more, and expression of Bcl-6 was detected in 10 cases. For patients with pure DLCL, overall survival was sig nificantly (p <0.05) worse than those of high-grade MALToma and CD10-positi ve DLCL by Kaplan-Meier and log-rank methods. Clinical staging and Bcl-6 ex pression were also good prognostic factors in patients with DLCL. Three gro ups of gastric DLCL each had unique histologic findings, immunohistologic c haracteristics, and prognosis.