Primary pancreatic cystic neoplasms of the pancreas revisited. Part IV: Rare cystic neoplasms

Primary pancreatic cystic neoplasms are being recognized with increasing frequency due to modern imaging techniques. In addition to the more common cystic neoplasms—serous cystadenoma, primary mucinous cystic neoplasm, and intraductal papillary mucinous neoplasm—there are many other less common neoplasms that appear as cystic lesions. These cystic neoplasms include solid pseudopapillary neoplasm of the pancreas (the most common rare cystic neoplasm), cystic neuroendocrine neoplasm, cystic degeneration of otherwise solid neoplasms, and then the exceedingly rare cystic acinar cell neoplasm, intraductal tubular neoplasm, angiomatous neoplasm, lymphoepithelial cysts (not true neoplasms), and few others of mesenchymal origin. While quite rare, the pancreatic surgeon should at the least consider these unusual neoplasms in the differential diagnosis of potentially benign or malignant cystic lesions of the pancreas. Moreover, each of these unusual neoplasms has their own natural history/tumor biology and may require a different level of operative aggressiveness to obtain the optimal outcome.

► Apart from the three common primary pancreatic cystic neoplasms (serous cystic neoplasms, mucinous cystic neoplasms, intraductal papillary mucinous neoplasm), other rare cystic pancreatic neoplasms can be encountered in clinical practice.
► Accurate preoperative identification is not usually possible.
► Surgery is typically required to establish the diagnosis.
► Prognosis depends on the histological type of the neoplasm.