serrated polyposis syndromeに合併した粘膜下層浸潤を呈した早期大腸癌の1例

Early Colorectal Adenocarcinoma with Submucosal Invasion Associated with Serrated Polyposis Syndrome, Report of a Case

要旨●患者は60歳代，女性．SPS経過観察目的に施行した大腸内視鏡検査で，下行結腸に約15mm大の0-IIa＋IIc型病変を認めた．病変中心部に隆起および発赤を認め，隆起部に陥凹面を伴っていた．NBI併用拡大観察では，表面構造の消失，著明に拡張し屈曲蛇行する血管を認め，JNET Type 2Bと診断した．色素拡大観察では，腺管開口部の内腔狭小化，辺縁不整，輪郭不明瞭が認められ，V_I型高度不整pitが最も近いと判断した．粘膜下層（SM）深部浸潤の可能性も考えられたが，小病変であるため診断目的にEMRでの一括切除を行った．病理組織像は，隆起辺縁部ではSSL，隆起部では中分化〜高分化管状腺癌であり，600μmのSM浸潤を来していた．本症例は，SPSに合併したSM浸潤を伴う早期大腸癌と考えられた．

　A woman in her 60s had a colonoscopy for surveillance of serrated polyposis syndrome. Colonoscopy discovered a 15-mm diameter 0-IIa＋IIc lesion at the descending colon. The central part was elevated and reddish, and the elevated area had partially depression. Magnifying endoscopy with narrow-band imaging revealed an amorphous pattern with thick vessels and vessel meandering in the central elevated part, and we diagnosed JNET（the Japan NBI Expert Team）Type 2B. Chromoendoscopy revealed no clear pit contour in the central elevated part, leading us to believe that the pattern was similar to a type V_I pit pattern. Although the endoscopic diagnosis indicated the possibility of submucosal invasive cancer, endoscopic mucosal resection was performed for diagnosis due to the small lesion.

　The histopathological evaluation demonstrated a sessile serrated lesion in the side part, moderate to well-differentiated adenocarcinoma, and submucosal invasion in the central elevated part.