微小胃癌の病理―微小胃癌の臨床病理学的特徴─未分化型微小胃癌の画像診断のために

The Histopathologic Feature of Minute Gastric Cancers─For Endoscopic Diagnosis of Undifferentiated Type Minute Carcinoma of the Stomach

要旨　早期胃癌1,319病変のうち，腫瘍径5mm以下の微小胃癌229病変（17.4％）を対象に病理組織学的特徴とマクロ所見の特徴を検討した．組織型は分化型が68.6％，混在型が8.3％，未分化型が23.1％であった．未分化型癌はM領域，前後壁に位置する頻度が高く，肉眼型は0-IIc型を呈する病変が多かった．未分化型0-IIc型癌の特徴は，円形・類円形，表面色調は，正色調，胃小区不明瞭化・消失，光沢感消失であった．マクロ的同定困難微小胃癌の頻度は，43病変（18.8％）で，未分化型に頻度が高かった．未分化型の同定困難微小胃癌の特徴は，M領域，小彎，萎縮性胃炎の程度（軽度），癌巣周囲粘膜（中間帯あるいは胃底腺），癌巣周囲の腸上皮化生（軽度）であった．

　We investigated 229 minute gastric cancer lesions in this study. Histologically, of the 229 lesions, 157（68.6％）were differentiated types, 19（8.3％）mixed type and 53（23.1％）undifferentiated types of adenocarcinoma. The characteristic histopathologic findings of the undifferentiated-type minute gastric cancers were“located in the M region of the stomach”, “located in the anterior wall or posterior wall of the stomach”, “0-IIc type of macroscopic type”. The characteristic macroscopic findings of 0-IIc type of the undifferentiated-type minute gastric cancer were“round or round-like in shape”, “normal color”, “obscurity of the gastric area”, “disappearance of luster”. The incidence of minute gastric cancers with difficult diagnosis macroscopically in all minute gastric cancers was 18.8％, and was found more frequently in the undifferentiated-type minute gastric cancers. The characteristic pathological findings of undifferentiated-type minute gastric cancers with difficult diagnosis macroscopically were“located in the M region of the stomach”, “located in the lesser curvature of the stomach”, “mild mucosal atrophy of the stomach”, “fundic gland region or intermediate zone of the surrounding mucosa”, “low degree of intestinal metaplasia in the surrounding mucosa”.