{"entity":{"id":"panin","kind":"term","name":"Pancreatic intraepithelial neoplasia (PanIN), the microscopic precursor of pancreatic cancer","aka":["PanIN","PanIN-1","PanIN-2","PanIN-3","Low-grade PanIN","High-grade PanIN","Pancreatic precursor lesion","Carcinoma in situ of the pancreas","Incipient IPMN"],"tldr":"PanIN is the name for abnormal cells lining the small pancreatic ducts that can, over years, turn into pancreatic cancer. It is too small to see on any scan and is found only under the microscope, so it cannot be screened for directly. Pathologists now grade it as low or high grade, and high-grade PanIN was found in about one in twenty-five older people who died without pancreatic cancer.","summary":"In 2001 eight expert pathologists, shown 35 duct lesions, used more than 70 different terms for them; a working group then agreed the term pancreatic intraepithelial neoplasia with criteria for PanIN-1 (flat or papillary, minimal atypia), PanIN-2 (moderate atypia) and PanIN-3 (severe atypia, carcinoma in situ), and agreement improved when the cases were re-reviewed (Hruban 2001). The 2015 Baltimore consensus replaced the three grades with two, low grade (former PanIN-1 and 2) and high grade (former PanIN-3, carcinoma in situ), to align reporting with clinical consequences; it also concluded that PanIN of any grade at the resection margin of a pancreas removed for invasive cancer has no prognostic implication, set 0.5 to 1 cm as the size at which a lesion may be either a large PanIN or a small IPMN (calling those with intestinal or oncocytic papillae or GNAS mutations incipient IPMN), and asked that the distance between an IPMN and an invasive cancer be measured to distinguish associated from concomitant carcinoma (Basturk 2015). PanIN carries the same early genetic events as the cancer, KRAS mutation first, then CDKN2A loss, with TP53 and SMAD4 changes at high grade. How common it is: when 173 autopsy pancreata without cancer or IPMN (mean age 80.5) were examined in their entirety, PanIN-1 was present in 77 percent, PanIN-2 in 28 percent and PanIN-3 in 4 percent; high-grade lesions were always multifocal, commoner with diabetes and older age, sat more often in the body and tail and in small ducts, and 71 percent were accompanied by cystic change and lobular fibrosis, features that endoscopic ultrasound might detect (Matsuda 2017). Because PanIN is invisible to imaging, surveillance programmes aim instead at its consequences, cystic lesions and small cancers, and research looks for its signature in pancreatic juice and blood.","asOf":"2026-09-24","wikipedia":"https://en.wikipedia.org/wiki/Pancreatic_intraepithelial_neoplasia","links":[{"label":"Hruban, Am J Surg Pathol 2001: pancreatic intraepithelial neoplasia, a new nomenclature (PanIN)","url":"https://doi.org/10.1097/00000478-200105000-00003"},{"label":"Basturk, Am J Surg Pathol 2015: Baltimore consensus, revised classification of pancreatic precursor lesions","url":"https://doi.org/10.1097/pas.0000000000000533"},{"label":"Matsuda, Pancreas 2017: prevalence of high-grade PanIN in 173 autopsy pancreata","url":"https://doi.org/10.1097/mpa.0000000000000786"}],"tags":["gi","pancreatic"],"related":[],"cancers":["pancreatic","ipmn-cystic-precursors","ipmn-associated-carcinoma"],"sections":[],"technologies":["pancreatic-surveillance","histopathology-ihc"],"targets":["kras","cdkn2a","tp53","smad4"],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":["pancreatic-cyst-high-risk-stigmata","tumour-grade","familial-pancreatic-cancer"],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"category":"Pathology"},"route":"/terms/panin/","neighbours":{"cancer":[{"id":"ipmn-cystic-precursors","kind":"cancer","name":"Intraductal papillary mucinous neoplasm and other pancreatic cystic precursors","route":"/cancers/ipmn-cystic-precursors/"},{"id":"ipmn-associated-carcinoma","kind":"cancer","name":"Invasive carcinoma arising in an intraductal papillary mucinous neoplasm (IPMN-associated carcinoma)","route":"/cancers/ipmn-associated-carcinoma/"},{"id":"pancreatic","kind":"cancer","name":"Pancreatic ductal adenocarcinoma","route":"/cancers/pancreatic/"}],"technology":[{"id":"pancreatic-surveillance","kind":"technology","name":"High-risk pancreatic surveillance (CAPS / PRECEDE)","route":"/technologies/pancreatic-surveillance/"},{"id":"histopathology-ihc","kind":"technology","name":"Histopathology & immunohistochemistry","route":"/technologies/histopathology-ihc/"}],"target":[{"id":"cdkn2a","kind":"target","name":"CDKN2A","route":"/targets/cdkn2a/"},{"id":"kras","kind":"target","name":"KRAS","route":"/targets/kras/"},{"id":"smad4","kind":"target","name":"SMAD4","route":"/targets/smad4/"},{"id":"tp53","kind":"target","name":"TP53","route":"/targets/tp53/"}],"term":[{"id":"familial-pancreatic-cancer","kind":"term","name":"Familial pancreatic cancer and inherited risk (who qualifies for surveillance)","route":"/terms/familial-pancreatic-cancer/"},{"id":"tumour-grade","kind":"term","name":"Grade","route":"/terms/tumour-grade/"},{"id":"pancreatic-cyst-high-risk-stigmata","kind":"term","name":"High-risk stigmata and worrisome features of pancreatic cysts (IPMN and MCN surgical criteria)","route":"/terms/pancreatic-cyst-high-risk-stigmata/"}]}}