炎症性腸疾患における生検診断のピットフォール―病理と臨床への提言

Pitfalls in Biopsy Diagnosis of Inflammatory Bowel Disease

要旨　現在の日本の生検診断は，Crohn病について辛く，潰瘍性大腸炎については甘い傾向にあるので，inflammatory bowel disease（IBD）≒Crohn病+潰瘍性大腸炎という理解を一般的にし，IBDであることは確実だが，両者の鑑別が困難な生検はIBD，NOS（not otherwise specified）と診断すべきではなかろうか．そうすれば二者択一による誤診が防げる．またIBDの生検診断基準は厳密でなければならず，IBDを示唆する所見があってもbasal plasmacytosisを欠く場合は，possible IBD，あるいはindefinite IBDと診断して，一過性大腸炎（acute selflimited colitis）との鑑別に努めるべきである．colitis，non-IBD typeと診断した場合は，原因追究の努力を怠らないことも重要である．

　In Western countries, inflammatory bowel disease (IBD) means ulcerative colitis (UC) and/or Crohn's disease (CD). However, this is not the common view of the Japanese pathologists, and their biopsy diagnosis frequently lean towards UC. Consequently, some cases of CD without epitholioid cell granuloma and self-limited proctocolitis with cryptitis and prominent round cell infiltration are misinterpreted as UC in biopsies.

　Biopsy diagnosis of proctocolitis should be as follows: 1: Definite UC. 2: Definite CD. 3: Definite IBD, probable UC or probable CD. 4: Definite IBD, NOS. 5: Probable or indefinite IBD, NOS. 6: Proctocolitis, non-IBD type. The most important histologic feature in colorectal biopsies of IBD is not cryptitis and/or crypt abscess, but might be basal plasmacytosis.