良性病変と鑑別診断の困難な隆起型早期胃癌―現状と今後の課題―内視鏡診断の立場から

Elevated Type of Early Gastric Cancer with Endoscopically Less Malignant Appearance: Recent Advance of Endoscopic Diagnosis

　近年の早期胃癌診断学の進歩とその普及は目覚ましいものがあり，量的には発見される早期胃癌数の増加，また，質的にはその形態像の変貌などの状況を生み出している．このことは同時に非癌病変に対する認識の変化や鑑別対象の質的変化をもたらしてきている．すなわち，良性病変と鑑別困難な早期胃癌の検討は，いつの時代においてもその時代における診断学の限界と将来の診断学の進むべき方向を示すうえで，常に1つの手掛かりを与え続けるものと考えられる．本稿では内視鏡診断の立場から，良性病変と鑑別診断困難な隆起型早期癌の診断学的意義，あるいは今後の課題などについて筆者らの得た最近の成績を中心に述べる．

　During the period from 1962 to 1981, 242 cases of solitary elevated type of early gastric cancer (Ⅰ, Ⅱa, Ⅱa＋Ⅱc) were resected at National Cancer Center Hospital. Out of the 242, 150 lesions showed definitely malignant appearance endoscopically, and in the remaining 92 (38％) differential diagnosis from benign lesions was necessary, because their endoscopic appearance resembled more or less to hyperplastic polyp (31 cases), gastric adenoma (32), verrucous (6), and nonspecific (23) gastritis.

　Chronologically, these benign-like cancers have been increasing year by year, and endoscopic appearance has been changing to be smaller and flatter. These results may be due to recent advance of endoscopic diagnosis, especially to popularization in biopsy sampling. In the 150 cases with definitely malignant appearance, however, the mean age was younger and the incidence of sm invasion was higher than that observed in 92 cases with benign-like appearance. This discrepancy was quite wide in the cases with the appearance similar to hyperplastic polyp or gastric adenoma. These results are paradoxical according to morphogenetic consideration, and may reveal that most of the cancers with benign-like appearance which have been detected until recently are not earlier lesions of the cancers with definitely malignant appearance.

　To make the detection of early gastric cancer more perfectly, much more attention should be paid not on the endoscopic appearance of hyperplastic polyp or gastric adenoma but on the other flat elevated appearances, such as hyperplastic or granular change of gastric mucosa as shown in case presentation of this paper. Because the mean age of these cases was younger than those that resembled hyperplastic polyp or gastric adenoma.