新鮮胃切除標本からみた最大径2cm以下の早期胃癌の深達度診断

Macroscopic Findings and the Invasivity of Early Gastric Carcinoma Less Than 2 cm in Size

要旨　外科的に切除された最大径2cmまでの早期胃癌436病巣（m癌333病巣，sm癌103病巣）について新鮮切除標本の肉眼像からみた深達度診断を検討した．sm浸潤の程度を，顕微鏡的浸潤（sm₁）と肉眼的浸潤に大別し，肉眼的浸潤を中等度浸潤（sm₂)と大量浸潤（sm₃）に分けた．病巣は隆起型，陥凹型，平坦型，およびそれらの複合型に分け，それぞれについて検討を加えた．隆起型では，sm浸潤が進むにしたがって表面の構造に乱れがみられ，sm₃では隆起全体が特徴的な平皿状を呈した．陥凹型では，細顆粒の出現や陥凹面の凹凸不整，なだらかな盛り上がりなどがsm₂～sm₃によくみられた．潰瘍の合併した病巣で線維化の強い場合には，従来いわれている粘膜ひだの所見のみからでは深達度の推測は難しかった．しかし陥凹面の詳細な観察が困難な低分化型癌では，粘膜ひだの所見も合わせて総合的に判断することが必要であると思われた．また1cm以上の陥凹性病巣では集中する粘膜ひだの中心から離れてみられる表面の細顆粒状の変化が，sm浸潤を表現している可能性が考えられた．2cm以下のsm癌のリンパ節転移は8例18％にみられ，sm₂が6例，sm₃が2例でⅡc型7例，Ⅱa＋Ⅱc型1例であった．

　To evaluate the invasivity of early gastric cancer from the macroscopic point of view, macroscopic and microscopic findings of 436 lesions of early gastric carcinoma, less than 2 cm in size, were analyzed. The lesions consist of 333 mucosal carcinomas and 103 submucosal carcinomas. In the elevated types (type Ⅰ and type Ⅱa) of early gastric carcinoma, irregular mucosa, small granular appearance, and erosion on the surface of the elevated lesion are possible signs of submucosal invasion. Central depression of an elevated lesion and entire flat elevation of the tumor suggest extensive submucosal invasion. On the other hand, most of elevated lesions with near normal surfaces were mucosal carcinomas.

　In type Ⅱc of early gastric carcinoma, a slightly granular appearance, irregular mucosa, and erosion on the mucosa of depressed lesion were signs of submucosal invasion. Drumstick formation and fusion of interrupted folds at the margin of the depressed area was not significant, because such findings were frequently found in cases with peptic ulceration of mucosal carcinoma. In cases of simple depression in which mucosal surface is almost normal, carcinoma was limited within the mucosa. Lymph node metastasis was found in 8 cases with sm₂ or sm₃ invasion.