潰瘍性大腸炎の癌・dysplasiaのサーベイランスにおける生検の役割―特に隆起型dysplasiaの生検の諸問題について

The Role and Pitfalls of Biopsy in Surveillance of Carcinoma and Dysplasia Associated with Ulcerative Colitis

要旨　潰瘍性大腸炎の癌・dysplasiaのサーベイランスにおける隆起型のdysplasia（DALM）の生検の役割・問題点を述べた．小さなDALMを含めれば，われわれのグループでのDukes AおよびBの浸潤癌には全例DALMを伴っていた．小さなDALMは，腺腫との鑑別が必要であるが，隆起の周囲粘膜からの生検で異型上皮を認めない場合，腺腫として内視鏡的切除し経過観察する適応があると考えられた．一方，比較的大きな隆起性病変で上皮表層には異型を認めず，深部に異型腺管や浸潤癌を認める症例もあり，生検診断の盲点と考えられた．平坦型dysplasiaの存在は十二分に心すべきだが，平坦粘膜からのランダムな生検の真の有用性はコストベネフィットなどの点では現時点でも評価不能であり，多様な形態を示す潰瘍性大腸炎合併腫瘍を念頭に置き，より小さなDALMにも注意して生検採取部位を選ぶ必要があると思われる．

　We described the role and pitfalls involved in biopsies during surveillance of dysplasia and cancer in ulcerative colitis. All our cases of invasive cancers associated with ulcerative colitis had DALM (dysplasia associated lesion or mass), if we carefully looked for a small DALM. As for the small DALM, differential diagnosis from adenoma is required. If biopsies from the surrounding flat mucosa around a mass show no dysplasia, we can carry out conservative treatment for the lesion as an adenoma. On the other hand, occult cancer in relatively large pseudo-polyps is a pitfall in biopsy diagnosis of a large mass in ulcerative colitis. Undoubtedly, we should be careful when diagnosing flat dysplasia, and it may be advisable to sample flat mucosa randomly. In any case, to improve diagnosis, we should make every effort to make a careful examination and note subtle differences.