5mm以下の大腸微小腫瘍の見つけ出しと取り扱い

Diagnosis and Management of Colorectal Tumors Less than 5 mm in Diameter

要旨　5mm以下の大腸腺腫の取り扱いについて，1～10年の経過観察を行った498病変の解析から，形態変化を来した病変の頻度は0.4％と低率で，①表面平滑な無茎性隆起型腺腫では2～3年の経過観察で十分であり，②結節状のもの，陥凹を持つものは積極的に切除する必要があるとの結論を得た．また，5mm以下の腫瘍の見つけ出しについて，61病変の表面陥凹型腫瘍を対象にX線診断能を調べた結果，X線発見率は28％と低率であるが，ルーチン検査の見直し診断では描出率は49％であった．X線検査の盲点はひだ上の病変，側面像で描出されている病変であった．微小腫瘍のX線診断能には限界があり，ルーチンX線検査で結節状の表面構造や陥凹の存在が疑われる場合は，積極的に内視鏡検査を併用し，内視鏡像との対比を行う必要があると考えられた．

　From the analytical results of 498 lesions with colonic adenoma less than 5 mm in diameter and in which the clinical course was followed up for from one year to 10 years, the incidence rate of these lesions with morphological change was low (0.4%). Our conclusions were: (1) A two to three year clinical course observation period for smooth surface-sessile protuberance-type adenomas was sufficient. (2) The nodular or depression-type adenoma should be excised without doubt or hesitation.

　Results of roentgenographic diagnosis of 61 lesions of surface-depression-type tumors less than 5 mm in diameter were investigated. It was found that only 28% of such tumors were detected on the first examination, but, when diagnosis by roentgenography was repeated, 49% of the tumors were detected. Lesions on folds and bilateral images were blind-spots for roentgenography. When nodular surface structure or depression is suspected by routine roentgenography, comparison with endoscopic patterns by concomitant use of endoscopy should be actively carried out because roentgenographic diagnosis capability for detecting micro-tumors is limited.