Hepatoid adenocarcinoma of the stomach. A clinicopathologic and immunohistochemical analysis

Background. The clinicopathologic and immunohistochemical features of the primary gastric hepatoid adenocarcinomas still remain unclear. Methods. The authors evaluated 28 hepatoid adenocarcinomas (HC) of the stomach on the basis of characteristic histologic features resembling hepatocellular carcinoma, which were selected from the 7200 cases of primary gastric carcinoma in their files. Additionally, 22 alpha‐fetoprotein (AFP)‐positive adenocarcinomas without hepatoid features (APC) were also selected. Results. The HC cases fell into the following two groups: HC with AFP‐positive tumor cells (Group 1; 15 cases) and HC without AFP‐positive cells (Group 2; 13 cases). Histologically, the glycogen granules and hyaline globules were common features in HC. The incidence of a venous invasion of HC (Groups 1 and 2) was higher than that of APC (Group 3). There were no significant differences among the three groups regarding clinical features, macroscopic features, and the incidence of lymphatic permeation. An immunohistochemical study showed that HC had differentiation into various directions. As for the advanced carcinomas, the 5‐year survival rates of patients with HC (Groups 1 and 2) and those with APC (Group 3) were 11.9% (21.4%, 8.3%) and 38.2%, respectively. The prognosis of Group 1 was similar to that of Group 2, but was poorer than that of Group 3. Conclusions. The findings suggested that HC, as shown by its characteristic histologic features, had a poor prognosis whether producing AFP or not, and that HC should therefore be distinguished from AFP‐positive carcinoma without hepatoid features.