小さな未分化型胃癌の特徴と組織発生

Distinctive Feature and Histogenesis of Undifferentiated Carcinoma of the Stomach

要旨　小さな未分化型胃癌の特徴と組織発生を検討するために，胃癌手術例のうち病巣の長径が1cm以下の114例122病巣を用いて検索した．純粋の未分化型癌（por，sig）の肉眼型はすべて陥凹型であり，皺襞集中があるものが多かった．占拠部位は，M領域の小彎に多く，C・A領域にあるものでも前壁・後壁にみられた．癌の発生する背景粘膜は，胃底腺領域と中間帯が多く，腸上皮化生がないか，あっても程度の少ない胃底腺域あるいは胃底腺の萎縮した胃固有粘膜上皮から発生すると思われた．一方，未分化型癌と分化型癌との混合型および腺窩上皮型癌は，臨床病理学的，組織学的にみて，純粋の未分化型癌と同様に，胃固有の粘膜上皮から発生するが，より萎縮，化生の進んだ粘膜上皮環境より発生すると考えられた．以上のことより，癌の組織型は，胃固有腺が萎縮し化生へと向かうにつれて，発生する癌の組織型が未分化型から分化型へ連続して変化してゆき，更に成長するにつれて成長する場としての粘膜環境の影響を受けて変化するものと考察した．

　One hundred and twenty-two lesions of small gastric carcinoma measuring 10 mm or less in the greatest diameter were histologically reviewed to clarify cellular origin of undifferentiated carcinomas.

　Histological classification of the 122 carcinomas were as follows: intestinal type differentiated carcinoma 78, gastric type differentiated carcinoma (foveolar type adenocarcinoma) 15, signet ring cell carcinoma or poorly differentiated adenocarcinoma (pure undifferentiated carcinoma) 9, mixed pure undifferentiated carcinoma and differentiated carcinoma (mixed type carcinoma) 10 and undetermined type carcinoma 10.

　Pure undifferentiated carcinomas were located in the fundic glandular zone, intermediate zone and/or mild intestinal metaplastic zone without fundic gland. On the other hand, mixed type carcinomas and foveolar type carcinomas were located in the intermediate zone and/or mild intestinal metaplastic zone without fundic gland.

　These facts suggested that both pure undifferentiated carcinomas and mixed type carcinomas arose from the proper gastric mucosa, and that mixed type carcinomas arose from the proper gastric mucosa with more atrophic and metaplastic changes than that for pure undifferentiated carcinomas.

　It is assumed that the histological type of gastric carcinoma changes continuously from pure undifferentiated carcinoma to differentiated carcinoma as the gastric mucosa changes from the proper type to the metaplastic type.