大腸腫瘍に対する拡大内視鏡観察と深達度診断―箱根シンポジウムにおけるV型亜分類の合意

Diagnosis of the Depth of Invasion of Colorectal Lesions using Magnifying Colonoscopy

要旨　拡大内視鏡を用いたpit pattern診断は，組織診断とよく対応している．V型pit patternはV_I（irregular）型とVN（non-structure）型に亜分類され，病理組織所見における腫瘍腺管の構造異型や癌浸潤巣の露出，異常間質の出現と関連し，V_I型pit patternは主としてm～sm_1b癌に，V_N型pit patternはsm_1c以深癌に対応した．V型pit patternの鑑別を行うことにより，早期大腸癌の深達度診断を正確に行うことが可能である．ただし隆起型sm深部浸潤癌ではV_N型pit patternを呈さない病変があり，現段階でのpit pattern診断の限界と考えられた．V型の亜分類V_I，V_Nの境界は箱根シンポジウムで合意された．

　There is good correspondence between histological findings and pit pattern using magnifying colonoscopy. Type V pit pattern is divided into VI (irregular) and VN (non-structure). The former represents severely dysplastic adenomas and slightly invasive submucosal cancers, whereas the latter represents deeply invasive submucosal cancers. Magnifying colonoscopy has been established as a useful clinical diagnostic modality for determining depth of invasion in colorectal lesions. However, protruded type lesions with type VI pit pattern are not uncommonly proved to be deeply invasive of the submucosal layer. We recognized the limits of diagnostic methods for pit pattern at the moment.

　1) Digestive Disease Center, Showa University Northern Yokohama Hospital, Yokohama, Japan