Histologic infiltrating pattern of gastric microcarcinoma by means of serial sections

Two hundred eighty serial histologic sections, 5 micron thick, were made of a very small gastric carcinoma with submucosal invasion in order to assess the initial infiltrating pattern into the submucosa, as well as the growth therefrom. The small carcinoma infiltrated into the submucosa through four independent small channels, 0.02 to 0.05 mm2 in size, despite its small spread (3 mm in diameter) on the mucosal layer. Each small channel always was accompanied by the small blood vessels penetrating the lamina muscularis. The size of carcinoma in submucosa grew further to reach 3 to 10 times small infiltrating sites of lamina muscularis mucosa. The growth pattern of the carcinoma in the submucosa, therefore, seemed to be an "expanded balloon." Moreover, a small but distinct vascular invasion could be demonstrated within the balloon, suggesting a possible vascular metastasis.