胃癌切除後7年目に発見され0-IIa型様形態を呈した単発性転移性大腸癌の1例

Solitary Metastatic Colon Cancer Detected as a Flat, Elevated Lesion 7 Years Following Gastric Cancer Surgery, Report of a Case

要旨●患者は90歳代，男性．7年前に胃前庭部癌に対し腹腔鏡下幽門側胃切除術を施行された．便潜血陽性に対するTCS（total colonoscopy）で下行結腸に8mmの0-IIa型病変を認めた．NBI（narrow band imaging）併用拡大内視鏡検査では，vessel patternは口径不同が目立たず，配列が不整で，分布が不均一であった．surface patternは不明瞭であった．クリスタルバイオレット染色併用拡大内視鏡検査では，窩間部のやや開大したI型pit patternを呈し，所見の乖離を認めた．病理学的検索で胃癌切除標本と酷似した所見かつ免疫組織化学染色がCK7（＋），CK20（−），cdx2（−）と大腸癌に非特異的な染色パターンであったことから胃癌の大腸転移と判断した．原発性大腸癌とは異なる内視鏡所見から転移性大腸癌の診断に迫ることができた症例であり，文献的考察を加えて報告する．

　We report a case of metastasis of gastric cancer to the descending colon in a male patient in his 90s with unusual findings on colonoscopy. He underwent distal gastrectomy for gastric cancer 7 years ago. Total colonoscopy revealed an 8-mm flat, elevated lesion in the descending colon with white-light imaging. M-NBI（narrow band imaging with magnification）showed that the vessel pattern had a regular caliber and an irregular distribution and arrangement, and the surface pattern was undefined. Magnifying imaging with crystal violet staining showed that the crypt orifice was round and the intervening part was slightly open. M-NBI shows it cancer but chromoendoscopy shows it normal mucosa. Finally, we diagnosed metastatic colon cancer from gastric cancer because the lesion was highly similar to a gastric cancer specimen in histological analysis, and the immunohistochemical staining patterns were CK7（＋）, CK20（−）, and CDX2（−）, which were nonspecific to colon cancer. This case report suggests that metastatic colon cancer can be diagnosed using endoscopic findings.