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Stomach and Intestine(Tokyo) Volume 22, Issue 4 （April 1987）

胃と腸 22巻4号（1987年4月発行）

Japanese English

今月の主題小さな大腸癌―早期診断のために

主題

大腸小早期癌の内視鏡的ならびに組織学的特徴―特に“flat elevation”とⅡaとの関連について Endoscopic and Histological Features of Small Early Carcinomas of the Colon with Special Reference to Flat Elevation and Ⅱa Type Carcinoma 武藤徹一郎 ¹ , 安達実樹 ¹ , 沢田俊夫 ¹ , 久保田芳郎 ¹ , 斉藤幸夫 ¹ , 大矢正俊 ¹ , 洲之内広紀 ¹ , 正木忠彦 ¹ , 森岡恭彦 ¹ Tetsuichiro Muto ¹ ¹東京大学医学部第1外科 ¹The First Department of Surgery, Faculty of Medicine, University of Tokyo pp.397-406

発行日 1987年4月25日 Published Date 1987/4/25

DOI https://doi.org/10.11477/mf.1403112735

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要旨　51個の1cm以下の大腸早期癌（小早期癌）と88個の“flat elevation”をポリペクトミー材料および手術材料より選び，内視鏡的ならびに組織学的特徴を検討した．小早期癌は広基性のものが最も多く，平坦病変はいずれもm癌であった．“flat elevation”88個の中にはm癌16個，sm癌4個が含まれており，癌化率は22.7％であった．癌化率は病変の大きさと共に増大する傾向がみられた．“flat elevation”は赤いわずかな隆起として認められ，ときに中心陥凹を伴っていたが，陥凹の有無と異型度との関係は認められなかった．m癌は1例を除いて腺腫成分を伴っており，adenoma-carcinoma sequenceが成り立つと考えられた．“flat elevation”として発見されたm癌はⅡa，Ⅱa＋Ⅱcの母地であり，いわゆる“de novo”癌と呼ばれる病変の多くもこの“flat elevation”から発生したと考えるのが妥当であると考えられた．大腸癌の新しい発生母地としての“flat elevation”の役割について考察を加えた．

　Fifty-one early carcinomas not more than 1 cm in size (small early carcinoma) and 88 flat elevations collected from polypectomy and operative specimens were analyzed colonoscopically and histologically. Flat elevation is defined here as a flat elevated lesion found on endoscopy and it is either adenoma or early carcinoma. On histology its height is almost twice as thick as surrounding normal mucosa. In small early carcinoma broad based type was the commonest and all of small flat type carcinomas were confined to the mucosa. Among 88 flat elevations there were 16 mucosal and 4 submucosal carcinomas making 22.7％ of malignancy rate. The malignancy rate of flat elevation increases with increasing size from 9.1％ to 55.6％. Most of flat elevations which were demonstrated as slightly elevated reddish lesions with occasional central depression were benign adenomas under 1 cm in diameter. No significant correlations between the grade of atypia and the presence or absence of central depression were noticed. All flat carcinomas but one contained adenomatous component suggesting adenoma-carcinoma sequence. Flat elevations were more frequently situated distally but flat carcinomas, classified as Ⅱa, showed even distribution. Although natural history of flat elevation is not clear at present, it is most likely to be an origin of Ⅱa or Ⅱa＋Ⅱc type of carcinoma and even so-called “de novo” carcinoma may arise from preexising flat adenoma. It is suggested that flat elevation (adenoma and carcinoma) can be another origin of colonic carcinoma.