拡大内視鏡で深達度診断が困難であった隆起型早期大腸癌の1例

Protruded Types of Early Sigmoid Colon Carcinoma whose Invasion Depth was Impossible to Diagnose Using Magnifying Endoscopy Observation, Report of a Case

要旨　患者は50歳代，男性．2010年6月に便潜血反応陽性の精査目的にて大腸内視鏡検査を施行，S状結腸に径12mm大の隆起性病変を認めた．通常観察にて緊満感を伴う病変で，拡大内視鏡観察ではV_I型pitを認めたが全体に腺管構造は保たれていた．SM浸潤の可能性も否定できなかったが，粘膜内癌を最も疑いEMRを施行した．病理組織診断はwell differentiated adenocarcinoma，SM2（5,350μm），ly0，v0，腫瘍の大部分でSM深部浸潤を認めた．大腸癌の深達度診断は，隆起型早期大腸癌では表面構造を保ったままSM深部浸潤を来す病変もあり，慎重な診断と治療法の選択が望まれる．

　A male over 60 years of age was referred to our hospital for further examination because of positive occult blood in his feces. Colonoscopy revealed a protruded lesion with expansive appearance, 12mm in size, in the sigmoid colon. Magnifying colonoscopy observation showed type Vi pit pattern, but micro-surface structures and crypt orifices were preserved from the border to the top of the lesion. We diagnosed it to be a mucosal carcinoma, but didn't rule out submucosal invasive carcinoma. EMR（endoscopic submucosal resection）was performed for total biopsy. Histopathological examination revealed well differentiated adenocarcinoma（tub1）with massive submucosal invasion（5,350μm, from the surface of the tumor）, ly0, v0. In the diagnosis of protruded colorectal carcinoma, magnifying endoscopy was useful for evaluating the degree of invasion. However, care should be taken in cases such as ours in which mucosal glands are preserved even though there are submucosal invasive lesions.