The role of Helicobacter pylori in primary gastric MALT lymphoma

Aims: Helicobacter pylori has been claimed to be an important aetiological factor which raises the risk of: mucosa-associated tissue lymphoid (MALT) l ymphoma. However, some studies on gastric MALT lymphoma revealed a low rate of H. pylori infection suggesting that not all gastric lymphomas are relat ed to H. pylori infection, The aim of this study was to verify the H. pylor i infection frequency in a series of patients with primary gastric MALT lym phomas and to examine the relationship between H. pylori and the pathologic al features of those lymphomas. Methods and results: Thirty-one cases of resected gastric lymphoma were ana lysed: 10 cases (32%) were low-grade MALT lymphomas and 21 cases (68%) were high-grade MALT lymphomas, Helicobacter pylori was found in only 18 of 31 (58%) cases. Helicobacter-pylori infection was significantly correlated wit h the grade and depth of invasion of MALT lymphoma since 63% of superficial low-grade MALT lymphomas were positive for H. pylori compared with 38% of advanced high-grade MALT lymphomas (P = 0.02). Conclusion: We confirmed the relationship between H. pylori infection and a subset of gastric MALT lymphoma. Our results also showed that not all low- and high-grade gastric MALT lymphomas are H. pylori-dependent. This sugges ts that H. pylori infection may play a promoter role in the development of MALT lymphoma, but its presence is not mandatory for the progression of the lymphoma in view of its low frequency in advanced high-grade MALT lymphoma .