Barrett食道癌の境界を読む―範囲と深達度：病理の立場から

Pathogenesis of Barrett's Esophagus and Barrett's Adenocarcinoma

要旨　小児・成人の食道胃接合部，成人の食道噴門腺の観察から，Barrett食道の成り立ちについての仮説を提唱し，そこからBarrett食道・腺癌にかかわる諸問題について考察を行った．結論　①Barrett食道は胃粘膜が食道側に連続的に伸び出した病態ではなく，食道噴門腺の露出による増殖能の活性化と下部食道粘膜の増殖幹細胞に潜在している円柱上皮への分化能の顕在化が関与して生ずる病態と推測される．②特殊円柱上皮がBarrett食道口側に観察される理由は，胃の影響が相対的に低い領域であり，食道扁平上皮の基底側に存在する増殖幹細胞は系統発生学的により根原的な腸型上皮への分化を発現しやすいためと考えられる．③Barrett食道は多中心性に発生した円柱上皮の癒合により形成されると考えられ，一部の腫瘍性病変の非連続性や多発の問題は，腫瘍性病変がBarrett食道の形成過程に発生すると仮定すると容易に説明できる．④Barrett腺癌の治療にEMRが用いられるようになり，病変の範囲決定はより重要性を増してきた．今後症例を蓄積し，臨床・病理が肉眼所見，内視鏡像，顕微鏡所見を詳細に比較検討し，整合性のある診断基準を確立することが肝要であろう．

　We investigated not only Barrett's adenocarcinoma but also adult and neonatal esophago-gastric junction to examine the pathogenesis of Barrett's esophagus and Barrett's adenocarcinoma. The conclusions are ;

　a) Barrett's esophagus is not a condition which is made by the continuous extension of the columnar epithelium from the stomach, but is a condition produced by the following phenomenon, 1)activation of proliferation capability of the esophageal cardiac gland through its exposure to the surface, 2)activation of the differentiating potential to columnar epithelium in the stem cells located in the lower esophagus.

　b) The specialized columnar epithelium is generally observed on the oral side of the Barrett's esophagus. We think the reason is that, because the influence of the stomach is relatively low on the oral side of the Barrett's esophagus, the stem cells may become easily changed to columnar epithelium of the intestinal type, which is more primitive than gastric mucosa and esophageal squamous epithelium.

　c) Neoplastic lesion of the Barrett's esophagus sometimes shows discontinuation or multicentricity. This is closely related to the facts, 1)The neoplastic lesion arises in association with the development of the Barrett's esophagus, 2)Barrett's esophagus tends to show multicentricity in the early stage of its generation.

　1) Department of Pathology, Tokyo Medical ＆ Dental University, School of Medicine, Tokyo

　2) Department of Surgery, Tokyo Medical ＆ Dental University, School of Medicine, Tokyo