組織混在型早期胃癌の病理学的特徴

Pathological Characteristics of Early Gastric Cancer with Mixed Histological Types

要旨　分化型・未分化型の組織型混在のみならず，粘膜内の腫瘍で規約上の組織型が混在する組織混在型早期胃癌の病理学的特徴について検討した．主組織型が分化型癌である組織混在型癌は，単一組織型から成る純粋型癌と比較して，副組織型が分化型，未分化型に限らず，深達度などが進行した症例が多く，リンパ節転移率が高かった．今回の組織型基準を用いて導かれたリンパ節転移のない粘膜内癌の条件は，大きさおよび潰瘍の有無を限定しない分化型純粋型と潰瘍のない未分化型純粋型癌症例であった．組織混在型は副組織型の種類に限らず，ガイドライン上の内視鏡切除基準よりも厳しい条件でもリンパ節転移を有する症例を認め，組織混在型を含めた内視鏡治療適応基準を作成する必要があると考えられた．

　We analyzed the pathological features of EGC（early gastric cancer）with mixed histological types, for mixed cancer of undifferentiated and differentiated types and/or histological types of the classification. Mixed-type cancers, in which the main histological types were differentiated and the secondary types were not limited to undifferentiated and differentiated, were mostly advanced and revealed higher rates of lymph node metastasis, in comparison with pure-type cancers consisting of a single histological type. The conditions of intramucosal cancer without lymph node metastasis discovered by using these criteria of histological type, were differentiated pure-types that do not limit the tumor size and the presence or absence of intracancerous ulcer, and undifferentiated pure-types without ulcer. A few mixed-type cancers, not limited to the secondary histological type, were recognized as having lymph node metastasis, under more stringent conditions than the endoscopic resection criteria of the guideline. It is necessary to create new criteria for indication of endoscopic surgery including these mixed histological types.