粘膜下腫瘍の形態を示し術前に確診が得られなかった高分化型早期胃癌の1例

An Extremely Well Differentiated Adenocarcinoma of the Stomach Preoperatively Diagnosed as a Submucosal Tumor, Report of a Case

要旨　患者は42歳の男性で自覚症状はない。会社の検診で胃前庭部大彎前壁に約18mm大の隆起性病変を発見され，その後の内視鏡検査および生検で良性の粘膜下腫瘍と診断された．以後4年間にわたり経過観察されたが，次第に増大し径35mmとなり，中央陥凹が出現したため当院紹介入院となった．入院後の生検で悪性所見が得られず，ボーリング生検でも同様であった．超音波内視鏡検査で粘膜下に主座を有する病変であった．悪性の確診を得られなかったが，急速な増大を示すことと中央陥凹を認めることから，臨床的に悪性と判断して幽門側胃切除D₂郭清術BI吻合を施行した．病理組織学的に正常粘膜と鑑別が困難なほど分化した表面構造を持つ高分化型腺癌〔sm，n（－），H₀，P₀，M₀，ly₂，v₀，stage Ⅰa〕であった．

　During his 1990 annual upper gastrointestinal x-ray examination, a 42-year-old man was found to have an elevated lesion in the stomach. Endoscopically, the elevated lesion, 18 mm in diameter, was observed on the greater curvature of the antrum. The lesion was smooth-surfaced and sharply circumscribed, but four years later, it was accompanied with a small ulceration in its center. Vigorous biopsies proved it as being of Group Ⅱ. Since the lesion looked like a submucosal tumor with central ulceration and had grown rapidly, a distal subtotal gastrectomy was performed. Pathological diagnosis was a well differentiated adenocarcinoma (sm, n₀, H₀, P₀, M₀, ly₂, v₀, stage Ⅰa). The lesion was so well differentiated that the surface mucosa of the tumor was endoscopically normal and tiny biopsy specimens could not give a definite pathological diagnosis. Although this type of tumor is very rare, it is necessary to take it into consideration in the diagnosis of a submucosal tumor.