粘膜下腫瘍様の転移巣が先に発見された早期胃内分泌細胞癌の1例

An Early Gastric Endocrine Cell Carcinoma Detected after Remarkable Metastasis, Exhibiting Features of a Submucosal Tumor, Report of a Case

要旨　患者は55歳．男性．他院人間ドックの胃X線検査で穹窿部大彎に40mm大の粘膜下腫瘍様病変が発見された．前年の検診では指摘されておらず，急速に増大したGISTが疑われ，精査目的で当センターを紹介された．精査の結果，穹窿部の粘膜下腫瘍様病変とは別に食道胃接合部の胃側に約3/5周に拡がる0-IIa＋IIc型病変が認められ，生検では乳頭腺癌を認めた．胃全摘標本の病理組織学的検査では，食道胃接合部の病変は高分化型管状腺癌主体のSM2の早期癌で，粘膜内深部に3mm大の内分泌細胞癌が共存し，脈管侵襲を認めた．粘膜下腫瘍様病変は左噴門リンパ節が塊状に癒合した内分泌細胞癌から構成され，術前診断では2病変の関連性は確定できなかったが，食道胃接合部の胃癌からの転移と考えられた．本症例は原発巣の中の微小な内分泌細胞癌成分が，その強い転移傾向により転移巣が急速に発育した結果，原発巣より先に発見されることになった興味深い症例である．

　Gastric Endocrine Cell Carcinoma is a relatively rare disease. The prognosis of this disease is very poor because of its rapid growth, metastasis and invasion at its early stage. This paper presents a case of gastric endocrine cell carcinoma with remarkable lymph node metastasis. A 55-year-old man was found, during an annual health check at the neighbouring hospital, to have a submucosal tumor-like lesion 40 mm in diameter in the greater curvature of the fornix. He was admitted to our center for more precise examinations because the tumor was suspected of GIST. A IIa＋IIc type early gastric cancer located in the esophago-gastric junction was also found. A biopsy from the IIa lesion revealed papillary adenocarcinoma. Total gastrectomy was carried out under a diagnosis of early gastric cancer and GIST. We considered there was no relationship between the two tumors. Histological diagnosis of the resected specimen revealed that it was an endocrine cell carcinoma 3 mm in size occurring concurrently with adenocarcinoma. The submucosal tumor-like lesion was diagnosed as having metastasized to left para cardial lymph-node consisted of endocrine cell carcinoma.

　Remarkable lymphnode metastasis was found before the diagnosis of the primary tumor.

　The case is thought valuable in consideration of characteristics of endocrine cell carcinomas which exhibit a high-malignant potential.