炎症性腸疾患の鑑別診断―感染性腸炎を除く

Differential Diagnosis of Inflammatory Bowel Disease, by Excluding Infectious Enteritis

IBDが典型的な画像所見を示していればその診断は比較的容易であるが，典型的所見を欠く場合は診断に苦慮することが多く，様々な腸炎との鑑別が必要となる．診断困難な場合，慎重な経過観察によって初めて確定診断に至る例も少なくない．IBDと鑑別を要する腸炎のうち感染症以外の主要な疾患として，Crohn病（CD）との鑑別では，主に腸管Behçet病（BD）・単純性潰瘍，潰瘍性大腸炎，虚血性大腸炎，NSAID起因性腸病変（潰瘍型），collagenous colitisなどが挙げられる．UCとの鑑別では，主に腸管BD，CD，リンパ濾胞性直腸炎，NSAID起因性腸病変（大腸炎型），腸管アミロイドーシス，放射線性腸炎などが挙げられる．また，indeterminate colitisの定義として“UCとCDの所見が重複し”とあるが，具体的所見としてに統一されたものはなく，その診断は注意深く行わなければならない．本稿では，前述した疾患の画像を示しながら，IBDとの鑑別診断について述べる．

　If IBD（inflammatory bowel disease）shows typical image findings, the diagnosis is relatively easy, but when it lacks typical findings, we often rack our brains about a diagnosis, and differentiation from various forms of enterocolitis is required. When diagnosis is hard, there are a lot of cases which lead to a definitive diagnosis only after careful follow-up.

　For the differentiation with CD（Crohn's disease）, the main disease among enterocolitis, except for infections primarily including intestinal BD（Behçet's disease）and simple ulcer, UC（ulcerative colitis）, ischemic colitis, NSAID（nonsteroidal anti-inflammatory drug）-induced intestinal lesion（an ulcer type）and collagenous colitis. For differentiation from UC, we primarily include intestinal BD, CD, lymphoid follicular proctitis, NSAID-induced intestinal lesion（a colitis type）, intestinal amyloidosis and radiation colitis.

　A definition of IC（indeterminate colitis）includes“overlap of findings of UC and CD”, but there is no collective opinion about concrete findings. Therefore, the diagnosis of IC is difficult and must be carefully made.

　The author describe differential diagnosis from IBD while showing an image of the disease that we included above in this report.