幽門部大彎側前壁のⅡa様病変を内視鏡的に約10年間経過観察，最終的にⅠ分化型のm癌に推移した1例

Unusual Growth Pattern of Type Ⅱa Early Gastric Carcinoma

要旨　64歳，男性，10年間にわたるⅡa型早期胃癌の発育過程の追跡例を報告した．最初は幽門前庭部に見えたごくわずかな小隆起性変化を手がかりに，逐年的にその変化を追及し，内視鏡所見と生検組織診断の両面からその経過を検討した．その結果，ひとつのⅡa型早期胃癌の発育変貌の過程をみることができた．経過の途中で，ときに内視鏡ならびに生検組織所見の不一致をみ，総合診断に迷いも生じたが，最後には生検で癌が確診され，胃切除が施行された．癌は深達度m，23×15mm，Ⅱa型分化型腺癌〔腺窩上皮（胃）型〕であった．切除後得られたⅡaの組織所見から逆行性に生検組織を見直すと，癌と本質的に同じ組織像が，既に初期の生検組織内にもみられた．このことから高度に分化した初期の腺窩上皮型の癌の生検診断は極めて困難である点を指摘した．Ⅱa型の経過の内視鏡像は，最初から極めて緩徐に増大したが7，8年を経て完成し，最後の1年以内で急激に大きさが増大した．以上の事実から，胃癌の中には，かなり長期間粘膜内に存在し，その発育は極めて緩慢であるが，ある時点で急激に大きさを変え，様相が変わるものもある，という意味での隆起性癌のひとつのnatural historyを示した．

　1) A 64-year-old male was found to have a tiny mucosal elevation in the antrum of pylorus by endoscopy. The patient was followed regularly for 10 years before definitive diagnosis of carcinoma was established.

　2) This particular type Ⅱa gastric carcinoma exhibited an extraordinary slow growth pattern for the period of 7 to 8 years, then sudden acceleration in growth and changes in endoscopic pictures followed. This case also illustrates an important fact that a certain carcinoma can remain almost dormant within the gastric mucosa for a very long time before gaining an entirely different behavioral pattern.

　3) By repeat endoscopies and biopsies, the presence of carcinoma in mucosal elevation was finally established. Gastric resection followed. Surgical specimen revealed carcinoma to be localized with in the mucosa.

　4) Retrospective review of all the previous biopsy slides and comparison with surgical specimen was made. Very similar pathological findings to that of surgical specimen was found in some of the early biopsy slides. Cellular atypia and histological irregularities could have been interpreted as early type Ⅱa carci noma.

　5) This case illustrates difficulties in establishing the diagnosis of well differentiated foveolar type gastric carcinoma in early stages as regenerative inflammatory process can simulate the same.