Crohn病の新しい診断基準の有用性―外科切除例からみて

Utility of New Criteria for Crohn's Disease

要旨　Crohn病（以下CDと略）の新しい診断基準に，問題点があるかどうかを検討した．縦走潰瘍は，CDのほかに，閉塞性大腸炎，虚血性小腸炎，腸型Behçet病や単純性腸潰瘍にみられた．小腸では，腸間隔上の縦走潰瘍ないし炎症性ポリープを伴う縦走潰瘍はCDの確診所見となった．大腸の縦走潰瘍は，炎症活動期にあっては，粘膜色調と炎症性ポリープの有無でCDと虚血性（閉塞性）大腸炎は区別でき，粘膜の色調と平滑さとでCDとUCは区別できた．炎症が治癒しても，炎症性ポリープの有無でCDと虚血性大腸炎は鑑別でき，炎症性ポリープの丸みの有無や表面の平滑さ，および平坦粘膜の表面模様からCDとUCは鑑別できた．しかし，二次感染を伴ったCDや，完治し平滑粘膜となったUCの場合，肉芽腫の有無や粘膜筋板の肥厚など組織学的所見を重視する必要があった．敷石像は虚血性大腸炎，閉塞性大腸炎，Yersinia腸炎，回腸結核でもみられた．CDやYersinia腸炎は主に浮腫，リンパ管拡張，集簇性リンパ球浸潤から成り，黄白色調が強かったが，虚血性大腸炎と閉塞性大腸炎はうっ血や出血で赤色調が強く，これに浮腫による黄白色調も加わっていた．Yersinia腸炎ではびらんや浅い潰瘍が孤立リンパ濾胞やバイエル板に発生し，びらんや小潰瘍が縦走性を示さず，敷石像が明瞭でない点，漿膜下層や脂肪織に炎症が強く，肉芽腫内に好中球浸潤やapoptosisがみられる点がCDと鑑別の参考となった．回腸結核は赤い敷石像を呈し，乾酪壊死を伴っていた．CDとUCの炎症性ポリポーシスは，色調や粘膜模様が異なり，また癌に合併する炎症性ポリポーシスが肉芽腫を伴う場合は，ポリポーシスの周辺に浮腫はなく，縦走潰瘍を合併することもなかった．CDの新しい診断基準はCDの自然史からみて妥当なものであったが，CD以外の炎症性腸疾患をいかに除外してゆくかが大きな課題である，と考えられた．

　New criteria for Crohn's disease (CD) were applied to various inflammatory bowel diseases (IBD), to determine whether they are completely valid or not. The subjects were all surgically resected cases and consisted of 81 cases of CD, 36 cases of obstructive colitis (OC), 21 cases of ischemic colitis, 4 cases of ischemic enteritis, 6 cases of ulcerative colitis (UC), 2 cases of Yersinial ileitis, 2 cases of tuberculosis, 2 cases of intestinal Behcet's disease and 4 cases of cancer with inflammatory polyposis. All of them had more than one longitudinal ulcer, or cobblestone appearance (＋inflammatory polyposis).

　Longitudinal ulcer was observed in obstructive colitis, ischemic colitis, and Behçet's disease as well as in CD. Longitudinal ulcer of the small intestine was located along the mesentery in CD, but along the antimesenteric side in ischemic enteritis and Behçet's disease. Longitudinal ulcer of the colon developed over the colonic tenias in colonic inflammatory diseases. However, CD differed from ischemic colitis in mucosal color (yellow-white vs red) and inflammatory polyps (present vs absent), and from UC in mucosal color (yellow-white vs red) and mucosal texture (smooth vs rough). Cobblestone appearance was observed in CD, Yersinial ileitis, ischemic colitis, obstructive colitis and tuberculous ileitis. The former two were mainly composed of edema, dilatation of lymphatic channel and aggregates of lymphoid cells and showed a strongly yellow-white color, but ischemic colitis and obstructive colitis showed a strongly red color due to congestion and hemorrhage, and also yellow-white color due to edema. In Yersinial ileitis erosion and shallow ulcers occurred in lymph follicles or Peyer's patches but didn't arrange themselrees in a longitudinal line, inflammation was severe in the subserosal layer or fat tissue and neutrophilic infiltration and apoptosis was observed in some granulomas. These findings were useful markers to differentiate Yersinial ileitis from CD. Tuberculous ileitis showed red cobblestone appearance and was accompanied by caseating granulomas. In cases of colonic cancer with inflammatory polyposis and granulomas, edema was not observed outside the polyposis area and longitudinal ulcer was never observed.

　It is suggested that the new criteria for CD are useful for diagnosis of Crohn's disease, but how to differentiate CD from other inflammatory bowel disease showed be described in more detail.