食道胃接合部腺癌の内視鏡診断

Endoscopic Diagnosis of Esophagogastric Junctional Adenocarcinoma

要旨●「胃癌取扱い規約 第14版」^1）では食道胃接合部（EGJ）を“食道筋層と胃筋層の境界の上下2cmの部位を食道胃接合部領域”とし，内視鏡的なEGJの定義として“食道下部の柵状血管の下端”“胃大彎の縦走ひだの口側終末部”を挙げている．これらの所見を正確に観察するためには，深吸気時の観察が重要である．人間ドックで上部消化管内視鏡検査を受けた1,057例〔男性625例/女性432例，年齢中央値60（17〜93）歳〕を前向きに検討した結果，深吸気時に，胃のひだ上縁を564例，柵状血管下端を742例に認め，218例では共に観察できなかった．SSBEの頻度は728/1,057（69％）で，LSBEの頻度は0/1,057（0％），Barrettなしが111/1,057（11％），判定不能が218/1,057（21％）であった．食道胃接合部癌の鑑別診断には，通常観察における領域性（境界の有無）の観察と，NBI拡大観察における表面構造，血管構造の観察が重要である．また，EGJには扁平上皮，食道噴門腺，胃噴門腺，腸上皮化生が存在するため，その内視鏡的特徴を熟知する必要がある．炎症が高度の場合はPPI投薬後の再検が有用だが，病変が扁平上皮に被われて，範囲診断が困難となる場合もあり注意を要する．また，炎症異型にて生検診断が困難な場合もあるため，内視鏡診断と生検診断が乖離した場合は，内視鏡専門医および消化管専門病理医へコンサルトすることが重要である．

　According to the Japanese guidelines, Esophago-gastric area is defined as area within 2cm from EGJ（esophagogastric junction）. And, EGJ is defined as lower edge of palisade vessels or upper edge of gastric folds. The endoscopic observation of EGJ is sometimes difficult because of narrow space. Therefore, deep inspiration is useful to keep esophageal lumen wider and observe EGJ well.

　A consecutive 1,057 patients［Male 625/Female 432, Age：60（17-93）］examined by esophago-gastroscopy with deep inspiration were enrolled into this prospective study. Upper edge of gastric folds and lower edge of palisade vessels were observed in 564 and 742 cases, respectively. And both findings were not observed in 218 cases（21%）. The incidence of SSBE, LSBE and no Barrett was 728/1,057（69%）, 0/1,057（0%）and 111/1,057（11%）cases, respectively,

　The observation of demarcation of the lesion by WLI, surface and vascular pattern by NBI magnified endoscopy is important for the diagnosis of junctional cancers. There are squamous cell epithelium, esophageal cardiac gland, gastric cardiac gland and intestinal metaplasia around EGJ. Therefore, the endoscopic characteristics of such glands should be understood to diagnose junctional cancers.

　Re-examination after PPI intake is useful, when the patient had severe esophagitis. However, sometimes the cancer was covered by squamous cell epithelium. The lateral extension should be diagnosed carefully in such case. And, sometimes the histological diagnosis of biopsy is also difficult because of inflammatory atypia. Therefore, consultation for professional endoscopist and pathologist is necessary, when there was discrepancy between endoscopic and biopsy diagnosis.