HELICOBACTER-PYLORI AND NON-HELICOBACTER PYLORI BACTERIAL-FLORA IN GASTRIC-MUCOSAL AND TUMOR SPECIMENS OF PATIENTS WITH PRIMARY GASTRIC LYMPHOMA

There is an association between Helicobacter pylori (H. pylori) and ga stric mucosa-associated lymphoid tissue (MALT) and MALT lymphoma. Hist ologically, mainly non-specific stains are used to detect H. pylori, s uch as haematoxylin-eosin (HE) or modified Giemsa (MG). In this study, both a MG and a specific immunohistochemical stain (IMM) for H. pylor i (Dako B471) were performed on sequential slides of resected material containing tumour and non-tumorous gastric mucosa from patients with primary gastric lymphoma (n = 52). Special attention was paid to the p resence of non-H. pylori bacterial flora diagnosed by a positive MG (a ccording to form and localization) and a subsequently negative IMM. On all slides, bacterial density was scored semiquantitatively (grades 0 , 1, 2, 3). In total, 32 (61.5%) patients were H. pylori positive usin g IMM and 34 (65.4%) were non-H. pylori positive using MG. In 24 out o f the 34 patients, the non-H. pylori flora consisted mainly of cocci i n combination with rods in 15 patients, mostly in minor quantities; in another 10 patients, high numbers of both cocci and different types o f rods were present. Most non-H. pylori bacteria were localized superf icially, although in 22 patients minor,quantities of non-H. pylori wer e also seen in the glandular lumina. After all of the patients had bee n analysed, no differences in the density of H. pylori and of non-H. p ylori flora were found. Only when comparing patients who had a small-c ell lymphoma with those who had a large-cell lymphoma was a significan tly higher density of H. pylori found in the corpus mucosa of large-ce ll lymphomas and a higher prevalence of non-H. pylori was found in rum ours, in antrum or corpus, of patients with large-cell lymphomas. In c onclusion, with joint evaluation using MG and a H. pylori-specific imm unohistochemical stains, the proportion of H. pylori-positive gastric lymphoma patients was lower than in most previous studies but other ba cteria were found in a relatively high proportion. The role of the non -H. pylori intragastric bacterial flora identified in this study has t o be further elucidated in the aetiopathogenesis of primary gastric ly mphoma.