Gastric and intestinal diffuse large B-cell lymphomas are clinically and immunophenotypically different. An immunohistochemical and clinical study

Aims: To determine the immunophenotype of gastric and intestinal diffuse large B-cell lymphomas and investigate the clinical significance of patterns of antigen expression. Methods and results: Immunohistochemistry was performed for detection of CD10, Bcl-6, Bcl-2, MUM1 and p53 in paraffin-embedded tissue from 29 patients with primary diffuse large B-cell lymphoma of the stomach and intestine. Statistical analysis was performed using chi(2) and Fisher's exact tests. Survival data were analysed by the Kaplan-Meier method and compared using a log rank test. Thirteen of the 29 cases were of germinal centre phenotype (CD10+ or CD10-, Bcl-6+ and MUM1-). Sixteen were of activated B-cell phenotype (all CD10- and either Bcl-6-, or Bcl-6+ and MUM1+). Sixteen cases showed Bcl-2 expression. There was a statistically significant difference (P < 0.05) in immunophenotype of the neoplastic cells relating to tumour site. Of 15 gastric lymphomas, 11 were of activated B-cell phenotype and 9/14 intestinal tumours were of germinal centre phenotype. No significant survival difference was found between groups with regard to expression of any of the antigens investigated. Conclusions: Primary gastric and intestinal large cell lymphomas appear to show different patterns of antigen expression. This suggests that these tumours arise by different mechanisms and/or from different causes. Gastric diffuse large B-cell lymphomas are usually of activated B-cell phenotype that may reflect a relationship with low-grade gastric lymphomas of marginal zone type. Intestinal diffuse large B-cell lymphomas usually show a germinal centre phenotype, suggesting an origin from germinal centre B cells. In this study the tumour immunophenotype was not associated with any difference in survival.