内視鏡所見からみたinflammatory bowel disease unclassified（IBDU）の特徴

Endoscopic Features of Inflammatory Bowel Disease Unclassified（IBDU）

要旨●IBD（inflammatory bowel disease）であっても潰瘍性大腸炎（UC）とCrohn病（CD）の鑑別が臨床的に困難な場合に“IBDU（inflammatory bowel disease unclassified）”の名称が用いられている．IBDUは経過中にかなりの割合でUCまたはCDに診断名が変更されることから暫定的名称と考えられてきた．最近ではIBDUの中に新たなサブタイプが含まれるという考え方に変わってきている．しかしIBDUの明確な診断基準は存在せず，画像が提示された症例報告は乏しいのが実情である．本稿では本邦における報告例と自験例における画像所見をまとめ，IBDUの画像的特徴のパターンについて考察した．加えてESPGHANの小児IBD診断基準であるPorto criteriaについても紹介した．

　The term “IBDU（inflammatory bowel disease unclassified）” has been used for IBD（inflammatory bowel disease）patients where the clinical discrimination between UC（ulcerative colitis）and CD（Crohn's disease）is difficult. Since a substantial portion of IBDU cases are reclassified as either UC or CD during the disease course, it has been considered as an interim diagnostic term. However, currently, it has been shown that a considerable number of IBDU cases certainly remain unchanged for a long time, suggesting the possibility of IBDU as a distinct IBD subtype. There are limited reports that describe the endoscopic features of IBDU ; moreover, the diagnostic criteria of IBDU are yet to be established. In this article, we describe the features of IBDU in not only our published reports but also by other research groups and suggest the patterns of IBDU. Additionally, the Porto criteria for the diagnosis of pediatric IBD are digested.