胃型分化型腺癌の判定基準と病理学的特徴

Differentiated Gastric Adenocarcinoma with Gastric Phenotype: Its New Classification and Histopathological Characteristics

要旨　本研究の目的は，分化型胃癌の新たな細胞形質分類基準を作成し，それに基づいて胃型形質分化型癌の病理学特徴を明らかにすることにある．分化型胃癌351例中，胃型形質癌は61例（17.4％）で，そのうち腺窩上皮型が27例（7.7％），幽門粘膜型が34例（9.7％）を占めた．胃型分化型癌は腸型分化型癌に比べて未分化型化率（混合型癌の割合）が有意に高率であった（32.3％vs7.9％，p＜0.01）．また，胃型分化型癌は腸型分化型癌に比べ変異E-cadherin発現率が有意に高率であった（19.4％vs2.7％，p＜0.01）．変異E-cadherin発現陽性の粘膜内癌10例中8例において，分化型癌腺管の増殖帯から未分化型癌部分へかけて陽性細胞の連続分布が認められた．分化型微小癌の検討では，胃型形質癌21例全例で癌組織中心部の構造は胃固有腺のみから構成されていた．低異型度胃型癌の40.0％（2/5），低異型度複合型癌の30.0％（6/20），低異型度不完全腸型癌の9.7％（3/31）にそれぞれHelicobacter pylori（H.pylori）の癌腺管への直接付着が認められた．高異型度癌では細胞形質を問わずH.pyloriの癌腺管への直接付着は認められなかった．

　The aim of this study was to establish a new classifications for cellular phenotype of differentiated gastric adenocarcinoma and to clarify the pathological characteristics of gastric phenotype carcinoma. In 351 cases, the ratio of gastric phenotype carcinoma was 17.4% (61/351) : foveolar phenotype 7.7% (27/351) and pyloric mucosal phenotype 9.7% (34/351). There was a significantly higher rate of undifferentiation among gastric phenotype carcinomas than among intestinal phenotype carcinomas (32.3% vs 7.9%, p ＜ 0.01). Also, the incidence rate of mutant E-cadherin was significantly higher among gastric phenotype carcinomas than among intestinal phenotype carcinomas (19.4% vs 2.7%, p ＜ 0.01). It was observed that mutant E-cadherin-positive cells were distributed continuously from the proliferative zone of the differentiated carcinoma glands to undifferentiated carcinoma parts in eight of ten mucosal carcinomas. Central parts of the tumors were constituted of proper gastric mucosal elements in all 21 differentiated gastric microcarcinomas with gastric phenotype. As for microcarcinoma with low-grade atypia, Helicobacter pylori was directly attached to 40.0% (2/5) of microcarcinomas with gastric phenotype, 30.0% (6/20) of those with compound phenotype, and 9.7% (3/31) of those with incomplete intestinal phenotype. As for microcarcinomas with high-grade atypia, there was no lesion with direct attachment to H.pylori.