早期大腸低分化腺癌の1例

Early Poorly Differentiated Adenocarcinoma of the Colon, Report of a Case

要旨　患者は50歳代，女性．食思不振，体重減少の精査目的で下部消化管内視鏡検査を施行し，横行結腸に15mm大のひだ集中を伴う丈の低い隆起性病変を認めた．病変は褪色調でわずかな陥凹面を有し，病変中央にはやや発赤の強い一段丈の高い隆起を伴っていた．NBI拡大観察では，通常みられるようなcapillary patternとは異なった，屈曲，蛇行の強い，縮れたような血管所見が認められた．また，pit観察では，不整型の小型pitが不規則に配列しているのが観察されたが，不整の程度は弱く，また，明らかな領域性は認めなかった．総合的に病変はSM1までにとどまるものと考え，EMRを試みた．しかしながら，non-lifting signが陽性であり，ESDに切り替えた．病理結果は，粘膜病変が完全に保たれている中～低分化腺癌で，粘膜筋板下に著明なリンパ管侵襲像と線維化を認めた．

　A 58-year-old woman consulted a previous hospital with a complaint of anorexia and weight loss. She underwent colonoscopy and a 15mm flat elevated lesion was detected in the transverse colon. She was referred to our institution for endoscopic treatment.

　Conventional colonoscopic examination revealed a flat elevated lesion with a slight depression in the transverse colon. Stretching folds and a reddish nodule were observed in the lesion. Magnifying NBI image showed an unusual capillary pattern with irregular capillary vessels. Crystal violet staining, using the magnifying view, identified a slight irregular small pit but a well demarcated area was not recognized. Finally, we estimated the depth of this lesion was SM（submucosal）slight and tried to perform diagnostic EMR, but the non-lifting sign was strongly positive in this lesion. We performed ESD（endoscopic submucosal dissection）to achieve en-bloc resection. Histologically, the cancer was almost completely mucosal, but the tumor was composed of moderately and poorly differentiated adenocarcinoma that infiltrated into the SM slight layer with lymphatic vessel invasion and severe fibrosis.