隆起性境界領域病変（Ⅱa-subtype）の経過観察中にⅡa＋Ⅱc型早期胃癌の発生を認めた1例

Development of Ⅱa＋Ⅱc Type Early Gastric Cancer Seen During the Follow-up Study of a Protruding Border-Area Lesion (Ⅱa-Subtype), Report of a Case

　われわれは胃の良性ポリープ（Stout，Castlemanらのadenomatous polyp，Evans，Mingらのregenerative polyp）と，良性悪性の境界領域に属するⅡa様の隆起性病変（Ⅱa-subtype）を臨床的に経過観察し，その肉眼的形態の消長や，癌化の可能性について，生検組織学的に検討した成績を再三報告してきた．

　良性ポリープ（93例，141病変）の経過観察では，約25％で明らかな大きさの増大など，肉眼的形態の変化が認められたが，生検組織学的に経過を追跡した成績（94病変，6カ月以ヒ9年余に亘る期間）では，未だ癌化の徴候を認めたものはない．

　As the author has shown in No. 2, Vol. 10 of “Stomach and Intestine” under the title of “Gastric Mucosal Change and Sercetory Function as a Background of Elevated Lesion of the Stomach”, the incidence of gastric cancer that accompanies benign polyp of the stomach is relatively low (4％), while Ⅱa-subtype (protruding border-area lesion) is far more often associated with differentiated adenocarcinoma (20％). It has also been demonstrated that benign polyp and Ⅱa-subtype polyp have some different clinical backgrounds in many respects, In benign polyp the male is equally affected as the female, while in Ⅱa-subtype the male far outnumbers the female in frequency, Ⅱa subtype favor s persons stile more advanced in years as compared with benign polyps. Mucosal changes as a background picture of benign polyp consist in various atrophic changes of medium to high degree. Intestinal metaplasia is not necessarily so remarkable, On the other hand, almost all cases of Ⅱa-subtype display not only severe atrophic changes of the mucosa but conspicuous intestinal metaplasia as well. Correspondingly, hypochlorhydria is of higher degree in the latter. It has also been shown that protruding types of gastric carcinoma have clinical backgrounds more akin to Ⅱa-subtype than to benign polyp.

　The case here described shows development of Ⅱa＋Ⅱc differentiated adenocarcinoma arising out of the mucosa with severe intestinal metaplasia in the neighborhood of Ⅱa-subtype, which in itself has undergone no remarkable morphological changes both macroscopically and in histologic pictures of biopsy specimens all through the follow-up lasting more than six years.

　The present case is of great interest as showing some relationship between intesinal metaplasia, Ⅱa-subtype and differentiated adenocarcinoma. The nature of Ⅱa-subtype remains unclarified in many respects. Further investigations of such cases are deemed important in the elucidation of relationship common to these lesions.