早期胃癌の病理診断とそのピットフォール

The Histological Diagnostic Pitfall of Early Gastric Cancer

要旨　最近の病理学的進歩をふまえて，癌には低異型度，高異型度があり，それによる肉眼所見の差について述べた．また胃癌は粘液形質からみると胃型と腸型があり，従来あまり知られていなかった胃型形質を有した癌は組織型の変化を来しやすい．またその診断，特に低異型度癌は反応性変化との鑑別が極めて重要である．これに対して腸型粘液形質を有する癌は腺腫との鑑別が大事である．それを知ったうえでの病理組織診断を行うことによりピットフォールに陥る危険を避けることが可能である．

　We described adenocarcinoma differentiated type of the stomach can be classified into major two types from the difference of mucin phenotype, one is adenocarcinoma with gastric mucin phenotype and second with intestinal mucin phenotype, and third gastric-intestinal mucin phenotype. The detail histological and biological characters of adenocarcinoma with gastric phenotype is not well known, however, this type of cancer often reveals histologically low grade atypia and is similar to non neoplastic or reactive hyperplastic foveolar epithelium. It is very difficult to make correct histological diagnosis and differential diagnosis between neoplasia and non neoplastic condition. Gross findings of gastric type adenocarcinoma with low grade atypia is polypoid feature with superficial or flat extension in the mucosa (Ⅱb-like) . Biological behabior of gastric type adenocarcinoma transforms to poorly differentiated adenocarcinoma according to larger size of tumor which is over 10 mm in size. On the other hand, pure intestinal type of adenocarcinoma is histologically homologus feature which did not show heterogenous histological feature in the mucosa. We should know the existence of both type adenocarcinoma and these biological behavior.