Helicobacter pylori and lymphoid follicles in primary gastric MALT-lymphoma in Mexico.

We reviewed our cases of gastric MALT-lymphomas over a 12-year period at a national oncological referral center, the Instituto Nacional de Cancerología in Mexico City, looking for morphological evidence of Helicobacter pylori infection near the primary neoplasia. H pylori as well as lymphoid follicles and chronic active gastritis were carefully searched for in the adjacent mucosa. There were 23 (85%) low-grade and four (15%) high-grade MALT-lymphomas. H pylori microorganisms were found adjacent to the neoplasia in 23 cases (85%; CI 95% = 72-99%) but the lymphoid follicles were seen in 15 of 23 (65%; CI = 56-74%). Chronic active gastritis was present in 25 cases (93%; Cl = 90-95%). There was a close association between H pylori and gastric MALT-lymphoma. Lymphoid follicles were a reliable indicator of infection and the claimed pathophysiological substrate for MALT-lymphoma. We conclude that patients in whom gastric lymphoid follicles are detected, must remain under clinical follow-up since H pylori is a plausible promoter of neoplastic transformation.