Acinar neoplasms of the pancreas-A summary of 25 years of research.

Our understanding about the family of acinar neoplasms of the pancreas has grown substantially over the past 25 years. The prototype is acinar cell carcinoma, an uncommon variant of pancreatic carcinoma that demonstrates production of pancreatic exocrine enzymes, verifiable using immunohistochemistry, and exhibits characteristic histologic features. Related neoplasms include mixed acinar carcinomas such as mixed acinar neuroendocrine carcinoma and mixed acinar ductal carcinoma. In the pediatric age group, pancreatoblastoma is also closely related. Cystic and extrapancreatic forms have been described. These neoplasms share molecular alterations that are distinct from the more common ductal and neuroendocrine neoplasms of the pancreas. Although there is a broad range of genetic findings, a number of potential therapeutic targets have emerged. This review explores the clinical and pathologic features of pancreatic acinar neoplasms along with their more common molecular phenotypes. The differential diagnosis with other pancreatic neoplasms is explored as well.