胃と腸42巻3号

2007年03月発行

今月の主題 大腸鋸歯状病変の発育進展と診断・取り扱い

主題

大腸鋸歯状病変の発生と発育進展―発育進展―鋸歯状腺腫と過形成性ポリープの癌化

著者： 原岡誠司¹ 岩下明徳¹ 太田敦子¹

所属機関： ¹福岡大学筑紫病院病理部

ページ範囲：P.288 - P.298

文献概要

要旨　癌を合併した鋸歯状腺腫（SA）14病変および癌を合併した過形成性ポリープ（HP）11病変について，臨床病理学的に検討した．発生部位は癌合併SAの64％，癌合併HPの80％が盲腸～横行結腸であり，右側結腸に多くみられ，病変の大きさは両者ともに平均16mmであった．肉眼形態は癌合併SAは有茎性隆起が多く，癌合併HPでは無茎性隆起が多かった．癌の多くは粘膜内に限局する高分化腺癌で，SA成分やHP成分より構成割合の少ない病変が多く認められた．免疫組織学的にcytokeratin（CK）7は，癌合併SAにおけるSAで35.7％，癌部で50％に陽性であり，癌合併HPではHPで27.3％，癌部では36.4％が陽性であった．特に癌合併SAにおける癌部の50％はCK7＋/CK20＋であった．癌を合併するSAおよびHPにおけるCK7の発現頻度は癌病巣で最も高く，次いでSA，HPという傾向がみられた．粘液形質の発現については混合型（胃腺窩上皮型＋腸型）粘液形質の発現（MUC5AC＋/MUC2＋）を示すものが，癌合併SAにおけるSAで78.6％，癌部は42.9％，癌合併HPのHPは全病変で，その癌部では90.9％を占めた．癌合併SA病変において胃型粘液形質を発現する頻度は高く，癌合併HP病変においてはその多くがHP，癌成分ともに胃型粘液形質を発現していた．以上より，SAおよびHPに合併する癌は，通常の大腸癌とは異なる，併存病変に類似した免疫組織学的特徴を有するものがあり，SAおよびHPは一部の大腸癌の前駆病変であることが示唆された．

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