Prevalence of subtypes of intestinal metaplasia in the general population and in patients with autoimmune chronic atrophic gastritis.

BACKGROUND: Gastric intestinal metaplasia (IM) is seen mostly in association with chronic gastritis, induced either by Helicobacter pylori infection or autoimmune mechanisms. IM can be categorized into three subtypes, where type III is associated with gastric carcinoma of intestinal type.
METHODS: Gastric biopsies from 475 subjects randomly selected from the general population and from 27 patients with autoimmune gastritis associated with pernicious anaemia were used. The criteria of Filipe & Jass were applied using different histochemical techniques in combination with haematoxylin and eosin stained material.
RESULTS: Twenty-three percent (109/475) of the subjects from the general population and 88% (24/27) in the group with autoimmune gastritis had IM. Type III IM occurred in 4% in both populations. Type III IM was located in the antrum in 90% in the general population. In the group with autoimmune gastritis, only one patient had type III IM, which was located in the corpus.
CONCLUSIONS: This study reveals for the first time the prevalence and distribution of subtypes of IM in a general population from the Western world. The comparatively high prevalence of type III IM in the general population (4%) indicates that its role as a precursor of gastric carcinoma may have been overemphasized. A similar prevalence of type III IM in patients with autoimmune gastritis may be considered low and suggests that mechanisms for gastric carcinogenesis other than the atrophy-metaplasia-dysplasia sequence could also operate in this condition.