NBI併用拡大内視鏡でも範囲診断困難な胃癌の特徴─中分化型や未分化型癌を中心に

Characteristic Findings of Difficult Cases to Diagnose Using ME-NBI

要旨●2013年8月1日〜2014年8月31日までの間に，ME-NBIによる範囲診断を行いESDを施行した早期胃癌468例の検討を行った．まず断端が陽性もしくは病理診断によるマップ図からマーキングの位置が大きく外れていた症例の検討を行った．断端陽性例と範囲診断誤診例26例はL領域に多く，組織型は分化型が12/26（58％），未分化型が11/26（42％）であった．次に術前に未分化型腺癌の診断でESDを施行した64例に対してESD時に病変の口側，肛門側にAPCでマーキング（128ポイント）を置き，切除後の病理標本でAPCマーキングの部分に切り出し線を入れ，誤差範囲1mm以内で口側と肛門側の位置を判定した．また，正診例，誤診例の増殖帯進展距離と背景の炎症細胞浸潤について検討した．114/128（89.1％）が正診された．平均腫瘍径は正診例で小さく，正診された症例は窩間部開大距離が誤診群に比べ広かった．増殖帯進展距離に有意差はなかった．炎症細胞浸潤について検討すると，正診例で炎症細胞浸潤が軽度であった．tub2の39例中minor成分にporがあった症例は13例あり，うち2例が手つなぎ型であった．組織型からみるとME-NBIでは範囲診断困難例は分化，未分化型を約半数の割合で認め，未分化型が圧倒的に多いというわけではなかった．未分化型は増殖帯進展について窩間部開大をみていくことで範囲診断の正診率を上げることができる．

　（1）We studied 468 cases of early gastric cancers using ME-NBI（magnifying endoscopy with narrow band imaging）；particularly, cases with positive horizontal margins and misdiagnosed horizontal margin cases were investigated. The number of cases with positive horizontal and misdiagnosed horizontal margins were 7/450（1.5%）and 21/450（4.7%）, respectively. These lesions were located on the M area and IIc type was the most frequent macroscopic type. Histologically, 15/27（%）cases with positive and misdiagnosed horizontal margins were of the differentiated type.

　（2）We studied cases of ESD（endoscopic submucosal dissection）of poorly differentiated adenocarcinoma. Before ESD, oral and anal sides were marked using ME-NBI. In total, 64 cases and 128 points were investigated. All points were confirmed by histology in correct. Further, the histological and ME-NBI findings were in agreement at 114/128（89.1%）points. Correctly identified cases were smaller in size than incorrectly identified cases. Furthermore, incorrectly identified cases had more inflammatory cell infiltration than correctly identified cases.

　（3）In this study, we examined 468 cases of early gastric cancer. The final pathological diagnoses were as follows：39 cases of moderately differentiated adenocarcinoma, 13 cases of poorly differentiated adenocarcinoma, and 2 cases of crawling type. The margin of the lesion was misdiagnosed using ME-NBI in 4/39（10.3%）cases. Out of these 4 cases, 1 case had crawling type and 3 cases had microtubule and poorly differentiated type.