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.