BACKGROUND: Primary gastric non-Hodgkin's lymphomas possibly develop in response to local infection by Helicobacter pylori (H. pylori). We investigated the presence of H. pylori and non-H. pylori flora histologically in small- and large-cell primary gastric lymphoma using a specific staining method. MATERIALS AND METHODS: Specimens of 52 cases of primary gastric lymphoma (17 small cell, 35 large cell) were stained with modified Giemsa (MG) and immunohistochemically using a polyclonal antibody against H. pylori (IHC). RESULTS: Thirty-two cases (61.5%) (small cell 76% versus large cell 53%, P > 0.05) showed immunoreactivity for H. pylori in the mucosa surrounding the tumor. Remarkably, there was localization of H. pylori in the neck of the gastric glands in 3 cases. Non-H. pylori flora was seen in 35 cases (76.3%) (small cell 53% versus large cell 74%, P > 0.05). In 20 cases, this non-H. pylori flora was mixed with H. pylori. Five cases showed no bacterial flora at all. CONCLUSIONS: (1) Using immunohistochemistry, the prevalence of gastric lymphoma cases with H. pylori (61.5%) approximates that of H. pylori in the normal population. (2) No statistical difference was found between the occurrence of H. pylori and non-H. pylori bacterial flora in small- versus large-cell lymphoma. (3) Our results suggest that H. pylori may not be the only etiologic factor in primary gastric lymphoma.
BACKGROUND: Primary gastric non-Hodgkin's lymphomas possibly develop in response to local infection by Helicobacter pylori (H. pylori). We investigated the presence of H. pylori and non-H. pylori flora histologically in small- and large-cell primary gastric lymphoma using a specific staining method. MATERIALS AND METHODS: Specimens of 52 cases of primary gastric lymphoma (17 small cell, 35 large cell) were stained with modified Giemsa (MG) and immunohistochemically using a polyclonal antibody against H. pylori (IHC). RESULTS: Thirty-two cases (61.5%) (small cell 76% versus large cell 53%, P > 0.05) showed immunoreactivity for H. pylori in the mucosa surrounding the tumor. Remarkably, there was localization of H. pylori in the neck of the gastric glands in 3 cases. Non-H. pylori flora was seen in 35 cases (76.3%) (small cell 53% versus large cell 74%, P > 0.05). In 20 cases, this non-H. pylori flora was mixed with H. pylori. Five cases showed no bacterial flora at all. CONCLUSIONS: (1) Using immunohistochemistry, the prevalence of gastric lymphoma cases with H. pylori (61.5%) approximates that of H. pylori in the normal population. (2) No statistical difference was found between the occurrence of H. pylori and non-H. pylori bacterial flora in small- versus large-cell lymphoma. (3) Our results suggest that H. pylori may not be the only etiologic factor in primary gastric lymphoma.