| Abstract: | Resected early gastric carcinomas (1,690 cases) and atypical epithelial proliferations (adenomatous lesions, 310 cases) were investigated by the 5 mm-wide step sections. There were two types of intestinal metaplasia; double-layer type, where intestinal metaplasia was in the superficial area with the remaining pyloric or pseudopyloric glands in the deep region of the propria mucosae, and single-layer type, where intestinal metaplasia was usually present in a single layer without remaining deep non-metaplastic glands. These two types of intestinal metaplasia were usually found in the same specimen, however, most of the atypical epithelial proliferations (adenomatous lesions) arose from the area of intestinal metaplasia showing a double-layer type. The mitotic activity was usually found in the transitional zone showing these double-layer intestinal metaplasia. Atypical epithelial cells arose in the transitional zone of the double-layer intestinal metaplasia and spread into the luminal side by budding or replacement of existing epithelial cells. However, the author suspected that the cells in the under area of the transitional zone reproduce non-atypical cells to supplement the cells in the existing pyloric or pseudopyloric glands. On the other hand, atypical epithelial proliferations of single-layer type were rarely found showing a concaved appearance. Some of them may arise from the intestinal metaplasia of single-layer type, where the mitotic region moved towards the lower 1/3 of the glands. It seemed likely that most of the well-differentiated adenocarcinomas arise with intimate relation to these two types of intestinal metaplasia, where the incidence of malignant change of each type has been unknown. |
