最大径4mmの深達度pT1a-MM食道小細胞型内分泌細胞癌の1例

Primary Esophageal Endocrine Cell Carcinoma of Small Cell Type, which was 4mm in Size and pT1a-MM in Invasion Depth, Report of a Case

要旨　患者は60歳代，男性．上部消化管内視鏡検査で，切歯列より35cmの胸部下部食道右壁に径4mm大の発赤調隆起性病変を認めた．隆起の立ち上がりはなだらかで，表面は非腫瘍性扁平上皮に覆われ，硬さを有し，上皮下主体の病変であった．ヨード染色では明らかな不染はなく，隆起頂部に淡染を認め，tatamimeは病変内で途絶していた．EUSでは第2，3層を主座に置く低エコーとして認識され第4層を圧排し，深達度はT1a-MM～SM1と診断した．NBI併用拡大観察では腫瘍表面の発赤部に一致し，拡張，口径不同を伴う横走する網状血管を認め，有馬分類のtype 4R（non-AVA）に相当した．生検でCD56（N-CAM）陽性の内分泌細胞癌（小細胞型）と診断された．以上より，明らかなリンパ節転移を認めないため，十分なインフォームドコンセント後，病変をESDにて一括切除した．病理診断はendocrine cell carcinoma（small cell type），pT1a-MM，ly0，v0，HM0，VM0，0-IIa，4×3mm，免疫染色ではCD56，chromogranin A，synaptophysinが陽性であった．術後に化学療法（standard FP 4コース）を施行し，術後7か月現在無再発経過中である．

　A male in his sixties undergoing conventional esophagoscopy was shown to have a reddish flat elevated lesion on the right wall of the lower thoracic esophagus. The base of the tumor arose gently and the surface of the tumor was red and smooth, covered with a non-neoplastic epithelium. Esophagoscopy after iodine staining revealed a weakly stained lesion. Circumferential folds were not observed within the lesion. EUS（20MHz）showed a hypoechoic mass lesion invading from T1a-MM to SM1. Magnifying endoscopy with NBI revealed irregularly arranged reticular microvessels（type 4R）without forming AVA. The biopsy specimen was diagnosed as endocrine cell carcinoma（small-cell type）. Because preoperative CT examination revealed neither lymph node nor distant metastasis, and the lesion invaded as deep as MM-SM1, we performed ESD for the lesion in en-bloc fashion. Histologically, the tumor was diagnosed as an esophageal endocrine cell carcinoma（small-cell type）, with tumor size being 4×3mm, 0-IIa, pT1a-MM, ly0, v0, HM0, VM0. Immmunohistochemically, CD56, chromogranin A and synaptophysin were positive for the tumor cells. After ESD, the patient was treated with adjuvant chemotherapy（FP 4 course）, and 7 months later, lives with no recurrence.