9) dysplasiaおよびcolitic cancerの診断 (2)

Magnifying Colonoscopy for the Diagnosis of Dysplasia and Colitic Cancer in Patients with Ulcerative Colitis

要旨　潰瘍性大腸炎（UC）の長期経過例では，dysplasiaやcolitic cancerが発生する危険性が高まることから，大腸内視鏡による定期的なサーベイランスが必要である．通常内視鏡観察では，限局した隆起や領域のある発赤，粘膜の凹凸不整などに着目することが早期発見に有効である．色素内視鏡観察により異常所見を認めた場合は，拡大内視鏡によるpit patternの評価を行う．当院では13例のdysplasiaと5例のcolitic cancerに拡大内視鏡診断を行ったが，IIIL型やIV型の腫瘍性pit patternを認める場合が多かった．UCに伴う炎症性変化やsporadic adenomaとの鑑別診断についてはさらなる検討が必要であるが，拡大内視鏡観察はdysplasiaやcolitic cancerの質的診断に有力な情報をもたらし，効率的なtarget biopsyを可能にする検査法として活用されている．

　We mainly evaluated the clinical usefulness of magnifying colonoscopy for the diagnosis of dysplasia and colitic cancer in patients with ulcerative colitis. Thirteen lesions of dysplasia in ten patients and five colitic cancers in four patients were observed by conventional and magnifying colonoscopy. On magnifying colonoscopy, most lesions of dysplasia and colitic cancer showed IIIs to IIIL or IIIL to IV or IV type pit patterns. Tumorous pits associated with theses lesions were similar to those seen in sporadic colorectal adenomas and cancers, but the pit density was slightly lower. VN type pit pattern was not detected in our patients, because the depth of invasion of all colitic cancer was limited to the mucosa. It was concluded that magnifying colonoscopy is useful for early detection and diagnosis of dysplasia and colitic cancer. However, further studies are necessary for estimating the role of magnifying colonoscopy in the diagnosis of dysplasia and colitic cancer in patients with ulcerative colitis.