粘膜下以深に浸潤したH. pylori未感染胃印環細胞癌の1例

A Case of Undifferentiated-type Invasive Gastric Cancer Occurring in a Helicobacter pylori Non-infected Stomach

要旨●患者は60歳代，男性．健診で胃癌を指摘され治療目的に当院へ紹介され受診となった．上部消化管内視鏡検査では背景粘膜に萎縮はなく，RAC陽性であった．胃前庭部前壁に辺縁隆起を伴う陥凹性病変があり，伸展不良のためcT1bと診断し，幽門側胃切除術を施行した．切除標本では粘膜内に印環細胞癌が優位に，粘膜下層以深には低分化腺癌が浸潤しており，印環細胞癌と低分化腺癌が混在していた．H. pylori未感染印環細胞癌は0-IIbまたは0-IIcが多く，腺頸部増殖細胞帯から発生し側方浸潤するが，粘膜下層以深に浸潤した場合は潰瘍性病変を作り，印環細胞癌から低分化腺癌へ移行し混在する像をしばしば呈する．

　The patient was a 60-year-old man. Screening upper gastrointestinal endoscopy revealed the presence of a small, superficial, depressed-type gastric carcinoma in the anterior wall of the gastric antrum. Histological examination of the biopsy specimen confirmed a diagnosis of signet-ring cell carcinoma. He had no history of Helicobacter pylori eradication therapy. Endoscopic examination of the background gastric mucosa revealed no evidence of atrophy or intestinal metaplasia. A regular arrangement of collecting venules（RAC）was observed at the incisura and in the lower gastric body on the lesser curvature. A CT scan indicated no evidence of lymph node or distant metastasis. A diagnosis of undifferentiated-type early gastric cancer（cTbN0M0）was made, and a laparoscopic distal gastrectomy was performed. The tumor primarily consisted of signet-ring cell carcinoma in the mucosa and a poorly differentiated adenocarcinoma in the submucosa. The poorly differentiated adenocarcinoma was accompanied by fibrosis and had infiltrated into the muscularis propria through the submucosa. The final pathological diagnosis was L, Type 0-IIc, 12×8mm, sig>por2, pT2（MP）, INFc, Ly0, V0, pPM0（90mm）, pDM0（62mm）. The background gastric mucosa showed an absence of atrophy or intestinal metaplasia, and inflammatory cell infiltration was within normal limits.