Introduction: Intraductal lesions occurring in the vicinity of the pancreatic cancer had been recognized and described almost 50 years ago, but their relation to the malignant tumor has remained rather speculative until recently. Moreover, researchers employed several dozens of terminologies preventing the comparison between the results of different groups.
Aim: The paper reviews the development of term "pancreatic intraepithelial neoplasia" (PanIN) and describes its pathological characteristics.
Methods: Data collected from the world literature and from own material.
Results: Introduction of the term PanIN was based on the accumulated data from molecular studies suggesting that these preneoplastic alterations are most likely precursor lesions of the ductal adenocarcinoma rather than hyperplastic changes. PanIN-1A, PanIN-1B, PanIN-2, PanIN-3 represent consecutive steps towards the malignant phenotype but they all share a common histological finding: an intact basement membrane around them.
Conclusions: It is highly desirable that this standardized nomenclature be uniformly applied in the histopathological reports of pancreatic specimens.