潰瘍性大腸炎の初期病変―臨床的特徴と進展様式

Aphthous Lesions of the Colorectum : Clinical Significance of the Initial Lesion of Ulcerative Colitis

要旨　大腸アフタ様病変から典型的潰瘍性大腸炎へと進展した6症例（初期アフタ群）について，アフタの内視鏡像，進展様式，臨床経過を分析し，潰瘍性大腸炎の初期病変としてのアフタの意義について検討した．また，潰瘍性大腸炎診断後の経過中に，大腸にアフタ様病変を認めた9症例（経過中アフタ群）についても同様の検討を行った．各群に認めた大腸アフタ様病変は，Ia型（平坦型・発赤と白点），Ib型（平坦型・白苔と周囲の紅暈）とII型（隆起型）の3群に分けられた．初期アフタ群では，II型アフタが6例中4例を占め，4例とも直腸主体で，アフタから典型像への直接進展がみられたのに対し，I型アフタの2例は，アフタ消褪後，別部位に典型像が出現していた．一方，経過中アフタ群は9例ともI型アフタで，Ib型アフタ4例全例が典型像への進展が認められたのに対し，Ia型アフタは5例中1例のみしか進展が認められなかった．以上より，II型アフタは潰瘍性大腸炎の初期病変と考えられ，またIb型アフタについても初期病変である可能性が示唆された．しかし，Ia型アフタについては，大部分が潰瘍性大腸炎の活動期や寛解期に出現する一部分症であると考えられた．

　Six cases with solely colorectal aphthous lesions progress to typical ulcerative colitis（Early aphtha）, and 9 cases with typical ulcerative colitis with aphthous lesions（Late aphtha）were analyzed in order to investigate the clinical significance of the initial lesion of ulcerative colitis. Endoscopically, aphthous lesions were grouped into 3 patterns : as ① Flat reddish mucosa with minimal depression（type Ia）, ② Flat white depression surrounded by reddish mucosa（type Ib）, and ③ Hemisphere-shape with minimal depression（type II）. In Early aphtha group, type II aphtha were observed in 4 cases and type I aphtha in 2 cases. Type II aphthous lesions in 4 cases appeared mainly in the rectum and progressed to typical lesions of ulcerative colitis. Type I aphthous lesions in 2 cases had not directly developed to typical lesions of ulcerative colitis. On the other hand, in the late aphtha group, type Ia aphtha were observed in 5 cases, type Ib aphtha were noted in 4 cases, but no type II aphtha was observed. Although only one case with type Ia aphtha had progressed to typical lesion of ulcerative colitis, all 4 cases with type Ib aphtha were changed into typical lesions of ulcerative colitis. These data suggest that type II and type Ib aphtha would be the initial lesions of ulcerative colitis. But type Ia aphtha would be the reactive lesion in the clinical course of ulcerative colitis.