多発性過形成性胃ポリープに併存したⅠ型早期胃癌（有茎性ポリポイド癌）の1例

Early Gastric Cancer, Type Ⅰ (Pedunculated Polypoid Cancer), Associated with Multiple Hyperplastic Polyps of the Stomach, Report of a Case

要旨　低頻度ながら，過形成性ポリープと鑑別の難しいポリポイド癌（過形成性ポリープの癌化ではない）がある．われわれは，このようなポリポイド癌と多発性過形成性ポリープとが同一胃に併存していた興味ある1例を経験した．患者は65歳の女性．胃前庭部に9個の隆起性病変を認め，うち1個から生検でGroupⅤが得られた．この病変は径1.6cmの山田Ⅳ型の隆起性病変であり，胃X線および内視鏡所見上良性ポリープとみなしうるものであった．ただ，ほかのポリープと比べると表面はより平滑で，暗赤色調が強く，血のにじむような微細な発赤がみられ，生検時硬い印象があった．病理組織学的にはΩ型の粘膜筋板を有する（ポリポイド癌）深達度mの乳頭状腺癌であった．他はすべて過形成性ポリープであった．

　In general, pedunculated polyps of less than 20mm diameter in the stomach are histologically, usually hyperplastic. However, there is a polypoid cancer which resembles a hyperplastic polyp. In the case reported here, polypoid cancer was associated with benign multiple gastric polyps. And it was indistinguishable from those.

　A 65 year-old woman was admitted to our hospital for a further check up of multiple gastric polyps. X-ray and endoscopic examination (Fig. 1-4) demonstrated nine polyps in the antrum of the stomach. Papillary adenocarcinoma was confirmed by biopsy from one polypoid lesion (No. 8). This lesion which resembled a benign hyperplastic polyp, was pedunculated and 16 mm in diameter. However, on biopsy, compared with other polyps, this lesion was harder and more dark-reddish in color than the others (Fig. 3-4). Pathohistological findings revealed papillary adenocarcinoma involving the mucosal layer with a villo-tubular pattern without lymph node metastasis (Fig. 5, 7). The muscularis mucosae of the polyp (No. 8) was omega-shaped and proved to be a polypoid cancer (not polypogenic cancer) whereas the other eight polyps were all hyperplastic polyps (Fig. 6 a-d).