Fig. 4

Histopathological findings of the primary lesion. A Hematoxylin and eosin staining findings. The tumor showed intraductal papillary growth of the atypical columnar epithelium with thin fibrovascular cores. The tumor cells contained abundant mucin and resembled crypt cells of the stomach. B–D Immunohistochemically, the tumor was MUC1- and MUC2-negative and MUC5AC-positive. These findings indicated that the tumor was of the gastric type