低異型度分化型胃癌―その病理学的特徴

Low Grade Differentiated Type Adenocarcinoma of the Stomach : Its Pathological Features

要旨　粘膜下層以深に浸潤した低異型度分化型胃癌12例12病変のホルマリン固定外科手術検体を用いて，その病理学的特徴を検討した．細胞形質からは胃腸混合型腺癌8病変，完全腸型腺癌4病変に大別された．癌性潰瘍部を除き，すべての病変で粘膜内癌巣が広い範囲で保存され，この粘膜内癌巣に対して腫瘍が末広がりに深部浸潤すると立ち上がりがなだらかな粘膜下腫瘤様の隆起を形成した．深部浸潤部における癌の異型度は粘膜内癌巣と同程度に低く，腺管構造は保たれていた．腸上皮化生を伴った粘膜を背景にもつ粘膜内癌巣の辺縁境界は不明瞭であったが，癌部粘膜の色調は概して褐色調であった．以上の特徴の指摘とともに低異型度癌と超高分化型腺癌の異同について見解を述べた．

　The aim of this study was to clarify the pathological features of low grade differentiated-type gastric adenocarcinoma. We studied 12 lesions from 12 cases with gastric carcinoma（invasion to the subumucosa, muscularis propria, subserosa and serosa : 5,2,3, and 2 cases, respectively）. Twelve lesions were classified into 8 lesions of mixed gastric and intestinal phenotype and 4 of completely intestinal phenotype.

　Macroscopically, the lesions with massive submucosal invasion presented submucosal tumor-like elevated lesions sloping up gently and covered with intramucosal carcinoma lesion without ulceration.

　Histologically, the lesions consisted of glandular proliferation extending down through the gastric wall to the deeper zone. The greater part of the lesion revealed mild cellular atypia which was difficult to diagnose as overt adenocarcinoma. The demarcation line of the lesions was difficult to identify since they were accompanied by typical intestinal epithelial metaplasia. The lesions appeared brownish in color.