中分化進行癌へと連続的に移行する組織像を確認しえた胃底腺型胃癌の1例

Gastric Adenocarcinoma of Fundic Gland Transforming into Moderately-differentiated Tubular Adenocarcinoma with Subserosa Invasion, Report of a Case

要旨●患者は6X歳，男性．胃がん検診の精密EGDで胃体中部小彎やや前壁よりに，辺縁にSMT様隆起を伴う境界明瞭な発赤陥凹面を認め，生検で分化型腺癌の診断を得た．抗H. pylori抗体価3U/ml未満であり，H. pylori未感染胃に発生した0-IIc型，SM以深への浸潤疑いで加療目的に当科に紹介となり，腹腔鏡下胃全摘術が施行された．切除標本では，病変中央の発赤陥凹面に一致して中分化腺癌が漿膜下組織まで浸潤しており，陥凹周囲の胃底腺粘膜深部には主細胞優位の胃底腺型胃癌が認められ，さらに腺窩上皮型の腫瘍腺管が加わって胃底腺粘膜型胃癌とも言える病理組織像に移行し，中分化腺癌まで連続的に病理組織像が変化する多彩な所見を呈する進行癌であった．

　A 67-year-old man was required to undergo close endoscopic examination in keeping with population-based screening for gastric cancer. Endoscopic findings revealed a reddish, depressed lesion accompanied by submucosal tumor-like elevation at the lesser curvature of the middle gastric body. Biopsy of the lesion revealed well-differentiated tubular adenocarcinoma. Serum anti-H. pylori antibody titer was below 3U/ml, indicating that the lesion occurred in an H. pylori-naïve stomach. The lesion was considered a 0-II type gastric cancer with deeper invasion beyond the submucosal layer, therefore a total gastrectomy was carried out. Pathological findings of the surgical specimen revealed the presence of a moderately-differentiated tubular adenocarcinoma invading into the subserosa at the center of the depressed lesion. In addition, a gastric adenocarcinoma of fundic gland（chief cell predominant）（GA-FG-CCP）covered by a non-neoplastic surface epithelium was found in the deep proper layer of the gastric mucosa surrounding the 0-IIc lesion. Contiguous with GA-FG-CCP, atypical glands mimicking the surface epithelium appeared in GA-FG. Their histological features came to resemble GA-FMG. The atypical features of these neoplastic glands gradually strengthened and then continuously shifted toward moderately-differentiated tubular adenocarcinoma. Finally, the lesion was considered as an advanced adenocarcinoma derived from GA-FG, accompanied by various intermediate features.