Intraductal and cystic pancreatic neoplasia.

The current WHO classification of digestive system tumours (2019) has presented the concept of diagnostics of intraductal and cystic neoplasms of the pancreas mostly based on integrated molecular data and evaluations of their malignant potential. Intraductal pancreatic neoplasms with ductal phenotype include microscopic precursor lesions of pancreatic ductal adenocarcinoma - the pancreatic intraepithelial neoplasia and macroscopic precursor lesions of pancreatic cancer, where intraductal papillary mucinous neoplasm represents the most common neoplasm of the pancreas with cystic appearance. Both intraductal oncocytic papillary neoplasm and intraductal tubulopapillary neoplasm are now classified as separate entities associated with less aggressive subtypes of pancreatic carcinoma and better prognosis. Clinical significance of microscopic pancreatic intraepithelial neoplasias is limited, in contrast to other intraductal neoplasms, which are presented as cystic and/or solid tumours by imaging methods with important consequences for further treatment and indication of surgical therapy (resection versus "watch and wait" strategies). Neoplasms of nonductal origin, such as acinar cell carcinomas and neuroendocrine neoplasms, can uncommonly display an intraductal growth and their correct classification has a great clinical importance. Moreover, differential diagnostics of cystic pancreatic lesions include not only cystic and pseudocystically transformed neoplasms, but also a large spectrum of reactive, inflammatory and dysontogenetic cystic lesions.