粘膜下腫瘍様の形態を呈した胃超高分化型腺癌の1例

Extremely Well Differentiated Adenocarcinoma of the Stomach Mimicking Submucosal Tumor, Report of a Case

要旨　症例は50歳代，男性．胃X線検査，内視鏡検査にて，胃角部後壁やや大彎寄りにひだ集中を伴う径3cm大の隆起性病変を認め，ひだの先端には明らかな蚕食像はなく，粘膜下腫瘍様を呈していた．拡大内視鏡では，病変部分は腸上皮化生の拡大像に類似しており，周囲の萎縮した背景粘膜の拡大像とも類似していた．EUSでも，腫瘍は粘膜下腫瘍様の形態を呈し，一部筋層への浸潤が疑われた．生検にて超高分化型腺癌が疑われたため，粘膜下腫瘍様の形態を呈する胃癌と診断し幽門側胃部分切除術を施行した．病理診断は，完全腸型の超高分化型腺癌〔SM2，0IIa＋IIc，ly0，v0，n（－）〕であった．

　A 50-year-old man visited our hospital with a complaint of epigastric pain in December, 2006. X-ray and endoscopic examination showed an elevated lesion like a submucosal tumor with fold convergence and irregular depression, measuring 3cm in size, at the posterior wall of the lower body of the stomach. Magnifying endoscopic view of the the tumor was analogous to that of intestinal metaplasia, and atrophic background mucosa. Endoscopic-ultra sonography also showed a hypoechoic lesion like a submucosal mass. Histology of the biopsy specimens revealed the possibility of carcinoma, so subtotal gastrectomy was performed. Histopathology of the resected specimen revealed an extremely well differentiated adenocarcinoma（EWDA）with complete intestinal phenotype〔SM2, 0IIa＋IIc, ly0, v0, n（－）〕.