A型胃炎に合併した胃底腺粘膜型胃癌の1例

Gastric Adenocarcinoma of the Fundic Mucosa Type with Type A Gastritis, Report of a Case

要旨●患者は60歳代，男性．2010年より悪性貧血の診断で当院内科外来に通院中，スクリーニング目的で施行した上部消化管内視鏡検査にて胃体部の高度萎縮と胃体下部前壁に平坦隆起性病変を認めた．病変は表面に血管透見像を伴う褪色調の腫瘍で，NBI併用拡大観察では病変に一致して不整な網目状構造を形成した異常血管を認めた．病変に対してESDを施行し，胃底腺に類似した腫瘍腺管から成る高分化型腺癌の所見を認めた．免疫組織化学的所見では腫瘍の大部分でpepsinogen I，MUC6が陽性で，CD10も軽度陽性を示した．表層にはMUC5AC陽性の腺窩上皮に類似した分化を呈する腫瘍が露出しており，いわゆる胃底腺粘膜型胃癌の所見であった．腫瘍の深部にECMを認め，抗胃壁細胞抗体，抗内因子抗体が陽性，血性ガストリン高値であることからA型胃炎に合併した胃底腺粘膜型胃癌と最終的に診断した．

　A man in his 60s was referred to our hospital to be screened for gastric cancer. EGD（esophagogastroduodenoscopy）showed a flat, elevated lesion on the anterior wall of the lower gastric corpus with severe atrophic changes of the gastric corpus. The tumor featured vascular ectasia of the faded tumor surface. Magnifying endoscopy with narrow-band imaging revealed an irregular microvascular pattern with an amorphous surface. Therapeutic endoscopic submucosal dissection was performed. The histopathological findings showed well-differentiated adenocarcinoma mimicking fundic gland cells, which were strongly positive for pepsinogen I and MUC6 and slightly positive for CD10. The carcinoma cells with positivity for MUC5AC was seen on the surface of the tumor. Type A gastritis was diagnosed as the reason for the endocrine cell micronest of the deep part of the tumor, hypergastrinemia, and positive antibodies to parietal cells and intrinsic factors. Diagnosis was gastric adenocarcinoma of the fundic mucosa type with type A gastritis.