this and the usual coexistence of adenocarcinoma with choriocarcinoma in the stomach suggest the possibility of a different mode of development of these tumors in the two sites : forward differentiation of neoplastic germ cells in the gonads and retrodifferentiation ( opisthoplasia ) of neoplastic mucosal epithelial cells in the stomach .
C0001418
adenocarcinoma
C0014597
epithelial