Pancreatic-type Acinar Cell Carcinoma of the Stomach Included in Multiple Primary Carcinomas

Background/Aim: Pancreatic-type acinar cell carcinoma (ACC) in the stomach is extraordinarily rare. We pathologically examined two cases with multiple primary carcinomas, including gastric tumors. Patients and Methods: Gastric cancer specimens were examined by immunostaining and electron microscopy. Results: Both cases had cancer cells with acinar patterns, resembling pancreatic ACC. The cancer cells in the first case were positive for exocrine markers, including chymotrypsin, lipase and alpha-1 antichymotrypsin (ACT), as well as neuroendocrine markers, including chromogranin A and synaptophysin. The cancer cells in the second case were positive for chymotrypsin and alpha-1 ACT, while being slightly positive for chromogranin A and synaptophysin. Ultrastructurally, cancer cells contained zymogen granules in both cases. The final diagnosis was pancreatic mixed acinar-neuroendocrine carcinoma and pure pancreatic ACC, respectively. Conclusion: We confirmed two cases with gastric pancreatic-type ACC included in multiple primary carcinomas. This type of double cancer has not been reported previously.