大腸癌の病理学的検討―特にpm癌の成り立ちについて

Histopathological Analysis of m, sm and pm Cancer of the Large Bowel

　診断技術が進歩したとはいえ，今日切除される大腸癌の多くは，進行癌であり，しかも筋層を越えた浸潤をみるものが大半を占めている．このうち，癌浸潤が筋層にとどまるものには比較的に先行病変の名残りをもっているものが多くみうけられる．そこでm癌とsm癌の検討を行いながらpm癌の成り立ちについて検索することは，腺腫の癌化という問題をも含めて，大腸癌の組織形態発生についての1つの推移経路が明らかにされると予想される．

　われわれは癌組織だけから成る微小m癌の経験はないものの，今回，特に粘膜筋板の形態や癌と共存する腺腫成分とに注意しながら，m，sm，pm癌の組織学的検討を行ったので報告したい．

　The pattern of invasion (spread) of colonic carcinoma involving the muscularis propria (pm cancer), especially the development of pm cancer from m cancer or sm cancer is investigated. The cases of m cancer (23 cases), sm cancer (42 cases) and pm cancer (72 cases) are analysed with regard to the presence or absence of the stalk and/or adenomas and the features of the muscularis mucosae.

　The features of the muscularis mucosae are divided into a narrowing type, intermediate type, broad base type and wavy-tortuous type. The wavy-tortuous type occurs with a concomitant sessile-type adenoma.

　In the m cancer, most of the cases are of the narrowing type which is characterized by a fountain-like elevation of the muscularis mucosae. In the sm cancer, it is partly replaced by the intermediate and broad base types, while in the pm cancer, the broad base type is predominant (60/72). The wavy-tortuous pattern (type) is observed in all three depths of invasion. Concomitant adenomas are recognized in 91.3% cases of m cancer, 73.8% of sm cancer and 26.4% of pm cancer. Based on these observations, it could be considered that many of pm carcinomas may develop from adenoma, showing a transition to the broad base type from the narrowing type via the intermediate type. The pm cancer may also develop from the m or sm cancer which has retained a wavy-tortuous type pattern. Regarding the low frequency of concomitant ademomas, however, the possibility of de novo cancer formation in the broad base type cannot be neglected totally.