Helicobacter pylori infection in gastric xanthomas: immunohistochemical analysis of 145 lesions.

A total of 145 paraffin-embedded biopsy samples of gastric xanthoma were analyzed for the localization of Helicobacter pylori (HP) antigens. By the indirect immunoperoxidase method using a polyclonal antibody, HP infection was identified on the surface of foveolar cells in 69 (48%) samples. In 38 (55%) of the 69 lesions, the HP antigens were demonstrated in the cytoplasm of xanthoma cells clustered in the actively inflamed lamina propria mucosae. Among the remaining 76 xanthoma lesions negative for HP infection on the epithelial surface, only eight (11%) showed the existence of HP antigens in the foamy histiocytes, and 39 (51%) revealed mild inflammatory change. Monoclonal antibody study using 75 specimens also gave a comparable result. Pre-embedding immuno-electron microscopy using paraffin sections revealed positively labeled rod-shaped bacteria both on the epithelial surface and in the phagosome of the xanthoma cells. These findings strongly suggest that some of the xanthoma lesions are provoked by lamina proprial invasion of surface-infected HP.