Incidentally discovered pancreatic intraepithelial neoplasia: what is its clinical significance?

Pancreatic intraepithelial neoplasia (PanIN) is a presumed precursor of pancreatic ductal adenocarcinoma (PDAC). We assessed the relationship between incidental PanIN after resection of non-adenocarcinoma lesions and the development of metachronous PDAC in the remnant.

We retrospectively reviewed the clinicopathologic data of patients who underwent pancreatectomy for non-PDAC from January 2000 to January 2010. Intraductal papillary mucinous lesions were excluded. All available postoperative imaging and clinical follow-up data were reviewed; the risk of developing PDAC was assessed in patients with a minimum follow-up time of 6 months and with imaging studies available for review.

A total of 584 patients were analyzed. Median age was 59 years (range 10-85 years), and 338 (58 %) were female. The most common lesions for which resection was performed were serous cystic neoplasms (17 %), pancreatic neuroendocrine tumors (38 %), metastatic tumors (9 %), and mucinous cystic neoplasms (7 %). PanIN was identified in 153 (26 %) patients. The majority of these patients had PanIN-1 or -2 (50 and 41 %, respectively), whereas 13 (8 %) had PanIN-3. Of the 506 (87 %) patients with adequate follow-up (median 3.7 years, range 0.5-12.6 years), 1 patient (0.2 %) with PanIN identified at the time of initial resection developed cancer in the remnant. This occurred 4.4 years after a distal pancreatectomy in the setting of PanIN-1B. No patient with PanIN-3 developed cancer during follow-up.

PanIN was identified in 26 % of patients who underwent resection for histopathology other than PDAC. The presence of PanIN of any grade did not result in an appreciable cancer risk in the pancreatic remnant after short-term follow-up.