微小胃癌の臨床診断の限界―特に内視鏡診断について

Electoronic Endoscopic Diagnosis of Minute Gastric Cancer

要旨　電子内視鏡検査で発見された微小胃癌31病変と見逃した12病変について，その臨床病理学的特徴と今後の対応について検討した．発見した微小胃癌の肉眼型は，Ⅱc（81％），Ⅱa（16％），Ⅱb（3％）の順であり，Ⅱbが他の報告に比して低率であった．最小のものは2mmの大きさであったが，3mmが一般的な診断限界と考えられた．また，見逃し例はⅡb（81％）が最も多かった．癌の組織構築をみると，未分化型癌の発見例は全層浸潤型であり中層浸潤型は見逃していた．分化型癌では，発見・未発見にかかわらず表層型と全層型浸潤がみられた．分化型癌には，色調や構造などを強調する画像処理が有用と考えられたが，中層浸潤型を呈する未分化型癌には，これらの画像処理も無効と考えられた．

　Forty-three lesions of minute gastric cancer, of which 31 cases were detected endoscopically, were analyzed clinicopathologically.

　(1) Electoronic endoscopic detection was routinely possible for lesions of over 3 mm in diameter.

　(2) Most cases of undifferentiated carcinoma were shown endoscopically as discolored areas. All cases which could be detected were, histologically, massive mucosal invasive type cancers. On the other hand, all cases which could not be detected were intermediate parts of mucosal invasive type.

　(3) In cases of massive mucosal invasive type of differentiated carcinoma, 21 of 26 cases (81%) were detected endoscopically. But, 5 of 10 cases (50%) of superficial invasive type could not be detected endoscopically.

　(4) Image analysis for undetected cases of differentiated carcinoma will be useful.