長期経過潰瘍性大腸炎に合併する粘膜変化に関する新知見

Unusual Mucosal Changes in Cases with Longstanding Ulcerative Colitis

要旨　長期経過した潰瘍性大腸炎のコロノスコピーによるfollow-up中に，癌，dysplasia以外の粘膜病変が少なからず発見された．これは大腸炎のない通常の大腸(without colitis)にはみられないものと，通常の大腸にもよくみられるものと2種類に分けることができた．前者は扁平上皮化生(1例)と広汎な拡がりをみせる過形成性扁平粘膜隆起(2例)であり，後者としては若年性ポリープ，通常型の過形成ポリープであった．10年以上経過した潰瘍性大腸炎41例にコロノスコピーを行い癌2例¹⁾のほかに上記のような粘膜変化を認めた．これらはすべて全結腸型，または亜全結腸型の症例にみられた．

　Longstanding ulcerative colitis (UC) is notorious for being accompanied by a high rate of occurrence of colon cancers and/or dysplasia. It is therefore, important to do follow-up colonoscopy for cases at high risk. During our surveillance-colonoscopy unusual mucosal changes were encountered (Table 1). For instance, we found squamous cell metaplasia, and extensive flat mucosal protuberance due to hyperplastic epithelial growth. We report here the following three cases (Table 2).

　Case 1: Squamous cell metaplasia, a 33-year-old male. Subtotal colitis of 15 years' duration. A well circumscribed pinkish-white mucosa was noticed at the sigmoid colon surrounded by healed mucosa (Fig. 1 a, b). The mucosa proved to be composed of squamous cell epithelium (Fig. 1 c).

　Case 2: Extensive and flat mucosal protuberance, a 67-year-old female. Total colitis of 26 years' duration. A widely distended mucosal growth with slightly villous superficial appearance was found at the lower rectum (Fig. 2 a). The lesion was composed of hyperplastic epithelium. No cellular atypism was noticed (Fig. 2 b).

　Case 3: Extensive and flat mucosal protuberance (multiple), a 30-year-old male. Subtotal colitis of 19 years' duration. There were three low and flat mucosal excrescences at the lower part of the rectum (Fig. 3 a-d). Their surfaces were smooth. They were similar in shape and size. The lesions proved to be hyperplastic in nature (Fig. 3 e).

　Although the clinical significance of these phenomena is not known, it is evident that the repeated mucosal damage and repair has something to do with these mucosal changes.