内視鏡検査からみたcolitic cancerの初期病変―遡及例の検討を含めて；通常内視鏡所見を中心に

Retrospective Study of Initial Lesions of Ulcerative Colitis-associated Colorectal Cancer on Endoscopic Examination : Focus on Conventional Endoscopy

要旨　潰瘍性大腸炎の長期経過例では，dysplasiaやcolitic cancerが発生する危険性が高まる．当院で通常内視鏡検査で評価しえたdysplasia 32病変とcolitic cancer 12病変の検討では，dysplasiaはcolitic cancerよりも短い罹病期間で発見されており，dysplasiaでは平坦粘膜や扁平などの表面隆起が多かったのに対し，colitic cancerでは結節状や広基性隆起など，dysplasiaよりも丈の高い病変が多くみられた．また，平坦な病変は限局した発赤や粘膜面の凹凸不整で発見されていた．遡及的検討では，LGD 15病変中5病変で経過観察中に形態の変化を認め，このうち4病変で組織学的にもHGDやcolitic cancerへの進展が認められた．形態変化したLGDの5病変は初回内視鏡検査で，領域のある発赤した平坦粘膜や扁平隆起，粘膜の凹凸不整，わずかな陥凹として捉えられていた．以上から，これらの所見はUC関連腫瘍の初期病変の可能性があることが推察された．

　Patients with long-term ulcerative colitis are at increased risk of dysplasia and CC (ulcerative colitis-associated colorectal cancer). In our hospital, 32 lesions of dysplasia and 12 lesions of CC were evaluated by conventional endoscopy. Dysplasia was detected in a shorter period after disease onset than CC. Many patients with dysplasia had flat mucosa or flat surface protrusions. In contrast, CC was often associated with higher lesions than dysplasia, such as nodular and broad-based protrusions. Flat lesions were detected in areas of localized redness or uneven, irregular mucosal surfaces.

　A retrospective study of 15 low-grade dysplasia lesions indicated that five lesions presented morphologic changes during follow-up. Four of these lesions histopathologically progressed to high-grade dysplasia or CC. Five low-grade dysplasia lesions with morphologic changes were characterized by flat mucosa with regional redness, flat protrusions, uneven irregular mucosa, and slight depression on initial endoscopy. These findings suggested the presence of initial lesions of ulcerative colitis-related tumors.