onductal Pancreatic Cancers

摘要

Nonductal pancreatic neoplasms, including solid pseudopapillary neoplasms, acinar cell carcinomas, and pancreatoblastomas, are uncommon. These entities share overlapping gross, microscopic, and immunohistochemical features, such as well-demarcated solid neoplasms, monotonous cellular tumor cells with little intervening stroma, and abnormal beta-catenin expression. Each tumor also has unique clinico-pathologic characteristics with diverse clinical behavior. To differentiate nonductal pancreatic neoplasms, identification of histologic findings, such as pseudopapillae, acinar ceil features, and squamoid corpuscles, is important. Immunostain-ings for acinar cell or neuroendocrine markers are helpful for differential diagnosis. This article describes the clinicopathologic and immunohistochemical features of nonductal pancreatic cancers. The pancreas is mainly composed of 3 types of epithelial cells: enzyme-producing acinar cells (85%), hormone-producing endocrine cells (3% to 5%), and ductal cells (up to 3%). In general, the most common epithelial neoplasm arises from the most common normal epithelial component in an organ. However, in the pancreas, the most prevalent tumors are not acinar ceil carcinomas (ACCs) but ductal adenocarcinomas. Because pancreatic neuroendocrine tumors (PanNETs) are discussed elsewhere in this issue (see Salaria SN, Shi C: Pancreatic Neuroendocrine Tumors, in this issue), they are not discussed here. Excluding PanNETs, nonductal pancreatic tumors comprise less than 5% of pancreatic neoplasms. This article discusses existing knowledge of these uncommon nonductal pancreatic neoplasms, including solid pseudopapillary neoplasms (SPNs), ACCs, and pancreatoblastomas (PBs).