純粋Ⅱb型早期胃癌の臨床病理学的観察

Early Gastric Carcinoma, Type Ⅱb: A CIinicopathologic Analysis

要旨　厳しい定義を満たす純粋Ⅱb 16例17病巣のうち，術前に癌の存在が診断されていたものは10病巣で，7病巣は病理組織学的検索で初めて診断された．組織型は13病巣が分化型癌，4病巣が未分化型癌であった．癌の発育様式は，病巣中心部では10病巣（59％）が表層型の拡がりを示し，発育先進部では11病巣（65％）が浸潤型の発育を示した，更に8病巣（47％）は中心部表層型，先進部浸潤型を示し，このような発育型式の組み合わせが，対照として用いた隆起型・陥凹型早期癌に比し多くみられた．他方，中心部で全層型発育を示す例もみられたが，このような例では構造異型の軽度な癌腺管より成っていた．また先進部で膨張型発育を示すものは全例分化型癌で，癌腺管の密度が低い傾向にあった．

　Of the 2,021 lesions of early gastric carcinomas in 1,857 patients, 17 lesions of the type Ⅱb were selected for the study. These lesions showed neither protrusion nor depression at the level of the surrounding non-cancerous mucosa, presenting no distinct margins, Among these, 13 were classified as differentiated type carcinoma and the remainlng 4 as undifferentiated type, 15 as intramucosal carcinomas and 2 as carcinomas with minute submucosal invasion. The mucosal layer was replaced by the malignant tissue only in the upper portion in 10 (59%) (superficial type) and in all the layer in 7 (41%) (full thickness type). The marginal portions of the lesions were infiltrative in 11 (65%) and expansive in 6 (35%). Undifferentiated type carcinomas always had infiltrative margins, although differentiated ones were either infiltrative o expansive in the manner of growthr. Unlike the types Ⅱa (elevated) and Ⅱc (depressed), the type Ⅱb had the tendency to spread superficially and/or infiltratively in the lamina propria mucosae. A smaller proportion of the type Ⅱb tended to grow with low grade of structural atypia, giving no recognizable alteration in the mucosal level.