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―病理の立場から

The Role of Biopsy in Surveillance of Carcinoma and Dysplasia of Ulcerative Colitis: From the Point of View of Pathology

要旨　病理医の立場から，UC（ulcerative colitis）の癌・dysplasiaのサーベイランスにおける役割を一言で言えば，癌，dysplasia，腺腫，再生異型を正確に診断することである．即ち，ポリペクトミーで治療可能な腺腫と大腸全摘出術を考慮すべきdysplasiaを的確に診断しなくてはいけない．次いでUC合併大腸癌には印環細胞癌や粘液癌が多いので，生検標本で少数の印環細胞や粘液を見逃さないことである．また，表層が鋸歯状腺腫のような組織像でも，進行癌のことがあるので肉眼像も大切である．更にUC合併PSC（primary sclerosing cholangitis：原発性硬化性胆管炎）には胆囊癌の合併もみられる．生検標本で再生異型かdysplasiaか鑑別困難な場合，p53染色が望ましく，また経験豊富な病理医にコンサルトするか，寛解期の再検が望ましい．UC合併大腸癌の約半数は直腸に発生するので，直腸で内視鏡を反転させ，注意深い観察と，多数の生検が必要である．

　From the point of view of pathology, the role of biopsy in surveillance for carcinoma and dysplasia in ulcerative colitis is to accurately diagnose carcinoma, dysplasia and adenoma and their recurrence. It is important to accurately differentiate an isolated incidental adenoma treated by simple polypectomy from dysplasia which may imply a need for colectomy. It is necessary to look carefully at mucus and small numbers of signetring cells, because there are many mutinous and signetring cell carcinomas in colorectal carcinoma associated with ulcerative colitis. Dysplasia or carcinoma is often confined to the basal portion of the crypts, whereas the upper portions contain more mature cells and a serrated pattern. Primary sclerosing cholangitis with ulcerative colitis is sometimes associated with gall bladder carcinoma. When the biopsy result falls into an indefinte category, a sensible approach is to repeat it. This will usually be after a period of medical treatment, as most of the difficulties encountered in such diagnosis arise from the presence of concurrent inflammation.