胃の肝様腺癌―疾患単位の提唱とその臨床病理学的特性

Hepatoid Adenocarcinoma of the Stomach: The nature of the disease; its entity and its clinicopathology

要旨　原発性胃癌で血清AFPの高値を伴う症例のうち，組織学的に肝細胞に類似する腫瘍細胞を含む症例9例を検討した．腫瘍細胞の産生するAFPのConA結合性やAFP以外の種々の肝細胞マーカーの検索から，腫瘍細胞は単に組織学的類似性にとどまらず，機能的にも肝細胞への分化を呈することが示された．われわれはこのような原発性胃癌を胃の肝様腺癌hepatoid adenocarcinoma of the stomachと呼ぶことを提唱し，併せて臨床病理学的特性を解析した．それによれば，本腫瘍は腸上皮型の高分化腺癌と密な関係を有する，予後不良な腫瘍である．

　Nine cases of primary gastric carcinomas, which had both markedly elevated serum AFP levels and foci of tumor cells with large, eosinophilic cytoplasms, were studied. They occurred in the antrum of the stomach of elder patients (Table 1). The tumors showed nodular, massive growth, and had poor prognoses because of frequent liver metastases. Histological examinations revealed that they contained medullary and/or trabecular proliferations of tumor cells, which were indistinguishable from neoplastic liver cells (Fig. 1-4). In addition, intramucosal, well-differentiated adenocarcinomas were consistently found (Fig. 5). Hepatoid and adenocarcinoma cells intermingled with each other. There were extensive venous involvements by tumor cells. Many tumor cells contained AFP, AAT, ACT, ALB, but not HCG (Fig. 8-10, 12, 15). PALB, TF, FER, PTB, and CEA were also demonstrated in some tumor cells (Table 2). There were different distributions between AFP-positive cells, and CEA-positive cells, the former being predominantly in hepatoid and the latter in adenocarcinomatous areas (Fig. 11-13). An ultrastructural study revealed that the tumor was composed of hepatoid cells, intestinal-type cells, and undifferentiated cells (Fig. 14). The patients' serum AFP could bind ConA in about 90％ of the total amount. These findings suggest that the tumor cells, at least in some foci, represent true hepatocellular differentiation. Thus we propose a new clinicopathological entity, hepatoid adenocarcinoma of the stomach and show that it has a close relationship to intestinal-type adenocarcinomas both cytologically and clinically.