It has been considered that gastric large B cell lymphoma mainly consists of mucosa-associated lymphoid tissue lymphoma (MALToma) with large cell transformation. However, debate continues about the cell lineage. We analyzed 61 operated cases of gastric B cell lymphoma, mainly focusing on 40 cases of diffuse large cell lymphoma (DLCL). Immunohistologically, two cases were classified as CD10-positive follicular lymphoma, 19 cases were low-grade MALToma, 11 CD10-negative DLCL with a component of low-grade MALToma (high-grade MALToma), 12 CD10-positive DLCL, and 17 CD10-negative DLCL without MALToma (pure DLCL). Lymphoepithelial lesion (LEL) was found in all -cases of high-grade MALToma, and in eight of these its invasion was confined to the mucosa and submucosa. Expression of Bcl-6 was detected in two cases of high-grade 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 positive for Bcl-6, and a delicate meshwork of CD35 (Ber-MAC-DRC)-positive follicular 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 significantly (p <0.05) worse than those of high-grade MALToma and CD10-positive DLCL by Kaplan-Meier and log-rank methods. Clinical staging and Bcl-6 expression were also good prognostic factors in patients with DLCL. Three groups of gastric DLCL each had unique histologic findings, immunohistologic characteristics, and prognosis.
From the Department of Pathology, Clinical Laboratory (M.T.) and Clinical Research Institute (K.I.), National Kyushu Medical Center Hospital, Fukuoka; Department of Pathology, Fukuoka University Chikushi Hospital (A.I.), Chikushino; Department of Pathology, Municipal Uwajima Hospital (K.K.), Uwajima; Department of Surgery, Municipal Munakata Hospital (H.H.), Munakata; and Department of Pathology, School of Medicine, Fukuoka University (S.U., M.K.), Fukuoka, Japan.
Address correspondence and reprint requests to Morishige Takeshita, MD, National Kyushu Medical Center Hospital, Jigyo-hama 1-8-1, Chuo-ku, Fukuoka, 810-8563, Japan; e-mail: firstname.lastname@example.org