学术论文

      Gastric atrophy, metaplasia, and dysplasia: a clinical perspective.

      Gastric carcinoma of the intestinal type originates in dysplastic epithelium, which in turn develops in the milieu of atrophic gastritis and intestinal metaplasia. Cancers also may develop less often from gastric adenomatous polyps, which represent dysplastic epithelium arising in a raised lesion. The main causes of chronic atrophic gastritis and gastric atrophy are autoimmune due to pernicious anemia or chronic Helicobacter pylori infection. In the former condition, there is severe atrophy of the corpus (oxyntic mucosa), with the antrum being speared. In contrast, chronic atrophic gastritis consequent to H. pylori infection is a multifocal pangastritis, involving independent foci in the corpus and antrum of the stomach. For the most part, these clinical conditions are silent; the only manifestation of both these forms of chronic atrophic gastritis is cobalamin (vitamin B(12)) deficiency. In the case of the autoimmune gastritis of pernicious anemia, cobalamin deficiency results form the absence of intrinsic factor. When cobalamin deficiency occurs in patients with H. pylori-related gastritis, for the most part, it is because these patients have hypochlorhydria and are therefore unable to release cobalamin from its bound form in food. Patients may have advanced neuropsychiatric manifestations of cobalamin deficiency and yet not be anemic, have a normal blood smear, and even have serum cobalamin levels in the normal range. The condition may be identified by demonstrating elevated levels of homocysteine and methylmalonic acid. Intestinal metaplasia may be of the enteric (grade I), enterocolic (grade II), or colonic (grade III) type. Grade III intestinal metaplasia has traditionally been thought of as the most sinister variety, although the extent of atrophy and metaplasia may be a better marker for premalignancy than the mere identification of small areas of grade III intestinal metaplasia. Over the years, there has been much disagreement and a high degree of interrate
      作者: Kapadia CR
      期刊: Journal of clinical gastroenterologySCI
      年,卷(期): 2003, 36(5)
      正文语种: eng