Gastric carcinoma resembling pancreatic mixed acinar-endocrine carcinoma

A case of gastric carcinoma resembling pancreatic mixed acinar-endocrine carcinoma of 77-year-old female is presented. This type of gastric tumor has not been previously reported. The endoscopic mucosal resection specimen of the fundus contained a 1.2 x 0.9 x 0.3 cm, well-circumscribed, tan, soft nodular tumor with protruded configuration with a central recess. Histologically, the tumor was confined to the mucosa and submucosa and was characterized by three growth patterns; acinar, solid, and glandular. The growth patterns were intermingled. The tumor cells in the acinar component had round nuclei with prominent nucleoli and diastase-resistant, periodic acid-Schiff-positive, eosinophilic cytoplasm. Immunohistochemically, the tumor cells were positive for CAM5.2, cytokeratin (CK) 7, CK 20, trypsin, lipase, alpha-1-antitrypsin, and alpha-1-antichymotrypsin. The tumor cells in the solid component were positive for Grimelius stain and chromogranin A. The findings indicated that the tumor showed acinar and endocrine differentiation. There was no heterotopic pancreas tissue in the specimen. The patient was well without tumor at the 7-month follow-up. It is important to know the existence of this type of gastric cancer and to not confuse it with a metastatic lesion of the pancreatic origin.