Pathogenesis of gastric lymphoma: The enigma in Hong Kong

Abstract

Background: Helicobacter pylori (H. pylori) infection has been postulated to be a pathogenetic factor in gastric lymphoma. However, the etiological factors for gastric lymphoma could vary in different populations. Materials and methods: We looked for histological evidence of H. pylori infection in 53 gastrectomy specimens from Hong Kong Chinese patients with primary gastric B-lymphoma. We also screened for Epstein-Barr virus (EBV) in these cases using in situ hybridization with oligonucleotide probes for EBV- encoded small RNA1 and 2. Results: H. pylori was found in 29 of 53 (55%), including 8 of 13 (62%) cases of low-grade lymphoma of mucosa-associated lymphoid tissue (MALT) type. These infection rates in gastric lymphoma are lower than those reported in Western populations (80% 100%) and comparable to that found in healthy Chinese blood donors (55%) or in non-ulcer dyspeptic patients (52% 57%). EBV was found in tumor cells only in one case of high- grade gastric lymphoma with low-grade MALT component which was H. pylori- negative, and in occasional nontumor lymphoid cells in 7 other cases. Conclusions: These results suggest that (1) the role of H. pylori in pathogenesis of gastric lymphoma may vary in different populations: (2) very few gastric lymphomas are associated with EBV; (3) not all low-grade gastric MALT lymphomas are H. pylori-dependent.