表層拡大型早期胃癌の病理―肉眼像と組織像の対比を中心に

Clinicopathological Characteristics of Superficially Spreading Early Gastric Cancer

要旨　表層拡大型胃癌の特徴を検討するために，3,218例の胃癌手術例を用いて検討した．早期癌と進行癌の癌の大きさ別の頻度から，長径7cm以上の早期癌（147例，早期癌の9.9％）を表層拡大型と定義し，4cm未満の通常型と比較検討した．表層拡大型は，相対的に女性の比率が高く，若年者に多かった．肉眼型は集中（＋）のⅡcが多く，組織型は印環細胞癌および低分化腺癌が多く，占拠部位は小彎を中心とした症例が大多数であった．更に典型的と思われる長径10cm以上の早期癌24例の詳細な検討では，肉脹型は陥凹型を主体とするⅡc様Ⅱb型と隆起型を主体とする粗大結節集簇型とに分類され，周辺では低い隆起を形成する傾向にあった．組織学的には，大多数の症例が胃型と腸型の混在する分化型癌と印環細胞癌との混合型あるいは印環細胞癌であった．肉眼所見と組織所見の対比では，印環細胞癌あるいは分化型のみから成る症例は肉眼的に境界明瞭であり，種々の組織型を呈する癌から成る症例は肉眼的に境界不明瞭であった．以上の結果から，表層拡大型胃癌は，腺窩上皮型癌や印環細胞癌を含む胃型の癌が周囲の粘膜環境と相まって小彎を中心に表層性に拡がった症例が大多数であり，臨床的には画像診断的および肉眼的にも境界不明瞭な症例が多く，注意が必要であると思われた．

　To investigate the characteristics of superficially spreading type cancers of the stomach, we reviewed 1,489 cases of early gastric cancers and 1,729 cases of advanced ones. In the former type, there was a high ratio of tumors smaller than 4 cm in diameter, but in the latter type, there was a high ratio of tumors larger than 5 cm in their greatest diameter.

　Comparative study was made between 147 cases of superficially spreading type early gastric cancers (larger than 7 cm in diameter) and 890 cases of common type early gastric cancers (smaller than 4 em). In the former, the ratio in female and young-age patients was high. Macroscopically there was a high ratio of Ⅱc with fold convergence, and histologically there was a high ratio of undifferentiated type adenocarcinomas. Most of the former lesions were mainly located on the lesser curvature. We also studied carefully 24 cases in which the cancers were larger than 10 em in diameter. Macroscopically, two types, mainly depressed Ⅱc-like Ⅱb lesions and roughly elevated nodular lesions were shown. Histologically two types were also shown, i.e., mixed gastric and intestinal type differentiated adenocarcinomas with signet-ring cell carcinomas, and pure signet-ring cell carcinomas. Macroscopically, tumor margins were unclear in cases of mixed histological types. We concluded that most of the superficially spreading early gastric cancers consisted of gastric type cancer cells, that were foveolar type adenocarcinomas and/or signetring cell carcinomas and had spread mainly in the lesser curvature with a background of a mild to moderate degree of atrophic gastritis. Clinically, carefull diagnosis of the tumor margin was required before operation.