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

Pancreatic-type acinar cell carcinoma (ACC) in the stomach is extraordinarily rare. We pathologically examined two cases with multiple primary carcinomas, including gastric tumors.Gastric cancer specimens were examined by immunostaining and electron microscopy.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.We confirmed two cases with gastric pancreatic-type ACC included in multiple primary carcinomas. This type of double cancer has not been reported previously.