潰瘍性大腸炎・Crohn病の鑑別診断における生検の役割―病理の立場から

The Role of Biopsy in Differential Diagnosis between Ulcerative Colitis and Crohn's Disease from the Pathological Viewpoints

要旨　潰瘍性大腸炎（UC）とCrohn病（CD）の肉眼・組織像，両疾患の生検診断に有用な組織像，両疾患の生検鑑別診断，“indeterminate”colitisなどについて，病理形態学的立場から概説した．その後で，上記事項を十分把握しているつもりの筆者らの施設における両疾患の日常生検診断の実態を分析した．その結果，UC（277人，生検回数699回）の生検診断の正診率は71.5％，CD（209人）の正診率は54％（大腸生検のみでは38.3％で，これに上部消化管生検での率を加えたもの）と予想外に低い値であった．これらの事実から，IBDの生検診断は考えられている以上に容易とは言い難く，その診断は，臨床像と経過，X線像，内視鏡像が主であって，生検診断はむしろ従であるとの認識が大切であることを強調した．

　We gave an outline of macroscopic and microscopic features of ulcerative colitis (UC) and Crohn's disease (CD), including differential diagnosis on biopsy specimens, and the indeterminate colitis from the pathological viewpoints, and then we analyzed an actual situation of biopsy diagnosis of both UC and CD in our institution where the concept of inflammatory bowel disease (IBD) was well understood. The accuracy rates of biopsy diagnosis were unexpectedly low as 71.5% (sample size: 277 patients, 699 biopsies) in UC and 54% (sample size: 209 patients) in CD. This accuracy rate of CD was calculated from the combined results of colon biopsy and upper gastrointestinal tract biopsy. The accuracy rate of CD from the result of colon biopsy only was 38.3%. Therefore biopsy diagnosis of IBD was so difficult that diagnosis of IBD should be made mainly by clinical pictures, course of the illness, and radiological and endoscopic pictures. The biopsy diagnosis may play a minor role in diagnosis of IBD.