小腸炎症性疾患の病理学的鑑別診断

Pathological Differential Diagnosis of Inflammatory Diseases of the Small Intestine

要旨　代表的な小腸炎症性疾患であるCrohn病，虚血性小腸炎（病変），腸結核，腸管(型)Behcet病，単純性潰瘍の特徴的肉眼像および組織像，主な病理学的鑑別点について概説した．Crohn病は特徴ある縦走潰瘍，敷石像，非乾酪性類上皮細胞肉芽腫，全層性炎症，裂溝などのうち前3者が比較的特異性が高く，病理診断にはこの3者の組み合わせが大切である．虚血性小腸炎は多岐にわたる成因が考えられるため，急性期，慢性期の特徴ある病理所見に加えて臨床情報が重要となってくる．腸結核は回盲部に好発する輪状潰瘍が特徴で，乾酪性肉芽腫ないしは結核菌を証明することで確定診断に至る．腸管(型)Behcet病および単純性潰瘍は回盲弁上に主潰瘍が好発し，多くは回腸末端にも娘潰瘍が併発する．小腸炎症性疾患の鑑別診断に際しては，特徴的病理形態像の把握とともに臨床情報も加えて総合的に判断することが大切である．

　We gave an outline of macroscopic and microscopic characteristic features of inflammatory diseases of the small intestine such as Crohn's disease, ischemic enteritis (lesion), intestinal tuberculosis, intestinal Behcet disease, and simple ulcer, including important pathological features for the differential diagnosis. The characteristic findings of Crohn's disease are longitudinal ulcer, cobblestone appearance, non-caseating epithelioid cell granuloma, transmural inflammation, and fissure. The former 3 findings are relatively specific and their combination is important for pathological diagnosis of Crohn's disease. Because the etiology of ischemic enteritis is multifactorial, the diagnosis of ischemic enteritis needs not only the characteristic histological features of ischemic enteritis in the acute or chronic phase but also clinical information. Intestinal tuberculosis typically involves the ileocecal region and reveals a circular ulcer. The confirmation of caseating epithelioid cell granulomas or acid-fast bacilli enables a definite diagnosis of intestinal tuberculosis. In intestinal Behcet disease and simple ulcer, the main ulcers characteristically occur in the ileocecal valve and the satellite ulcers frequently involve the terminal ileum. It is important to have a clear grasp of the characteristic pathological features in addition to clinical information for the differential diagnosis of inflammatory diseases of the small intestine.