小さい早期胃癌の病理組織学的研究―胃癌の組織発生の解明のために

A Histopathological Study of Small Early Gastric Carcinoma for Clarification of Histogenesis of Gastric Cancer

要旨　ほとんどすべて臨床的に見出された直径2cm以下の早期胃癌112例について，胃粘膜領域別に，組織型と周辺粘膜の腸上皮化生との関連を中心に検索し，癌の組織発生について考察した．胃底腺領域では，未分化型癌は腸上皮化生のない胃底腺を発生母地としていた．また，分化型癌の大部分では，軽度の腸上皮化生を伴う胃底腺から発生していた．未分化型癌と分化型癌の頻度はほぼ同じであった．中間帯では，未分化型癌は腸上皮化生を有しないか化生が軽度の粘膜を発生母地としていた．また，分化型癌の背景粘膜は腸上皮化生を中等度以上示すことが多かった．幽門腺領域では大部分の背景粘膜に中等度以上の腸上皮化生がみられたが，未分化型癌では一定の傾向はなかった．幽門輪から2cm以内の癌の大部分は，腸上皮化生の有無に関係なく，分化型癌であった．これらの検索から，未分化型癌は固有胃腺から，分化型癌は化生腸上皮から発生するという胃癌の組織発生の鳥瞰的概念は修正を必要とすべきことがわかった．

　One hundred and eleven small (less than 2 cm in diameter) early carcinomas of the stomach were collected from 803 cases of early carcinoma resected between 1980 and 1987 at Mitsui Memorial Hospital. All cases except for two were detected clinically. Relationship between location, histological typing, gross appearance and extent of intestinal metaplasia in the surrounding mucosa was investigated for clarification of cancer histogenesis.

　Mean age of patients with undifferentiated type carcinoma (40 cases) was 50.3 years which was more than 10 years younger than that of patients with differentiated type carcinoma (72 cases, 61.3 years). All of the undifferentiated type carcinomas grossly demonstrated depressed appearance, and approximately 60％ of the differentiated type carcinoma had depressed appearance and the rest had elevated or partly-elevated appearance.

　Of 19 carcinomas in the fundic gland region 10 were of undifferentiated type and 9 were of differentiated type. All undifferentiated-type carcinomas except one were surrounded by the fundic mucosa without intestinal metaplasia, indicating that cancers arised from the proper fundic glands. The majority of differentiated-type carcinomas were surrounded by the fundic mucosa with or without mild intestinal metaplasia. Only two differentiated carcinomas were accompanied by moderate or severe intestinal metaplasia. This fact suggested that differentiated carcinomas in the fundic gland mucosa arise either from the proper fundic glands or metaplastic glands.

　Thirty-nine cancers in the intermediate zone consisted of 18 undifferentiated-type and 21 differentiated-type carcinomas. Background mucosa of most undifferentiated-type carcinomas showed no or mild intestinal metaplasia, while that of most differentiated-type carcinomas showed more than a moderate degree of intestinal metaplasia.

　Out of 51 carcinomas in the pyloric gland mucosa there were 40 differentiated-type carcinomas, most of which were surrounded by mucosa with more than moderate intestinal metaplasia. Eleven undifferentiated carcinomas, however, had no close relation with the presence of intestinal metaplasia. On the other hand a great majority of carcinomas, located within 2 cm of the pyloric ring, revealed differentiated-type carcinoma regardless of the presence of intestinal metaplasia.

　These results suggested that histogenesis of gastric carcinoma is rather complicated and must be carefully considered, depending upon the mucosal location where carcinomas arise.