Noninvasive intraductal papillary mucinous neoplasms and mucinous cystic neoplasms: recurrence rates and postoperative imaging follow-up.

BACKGROUND: Although surveillance guidelines for resected invasive mucinous neoplastic cysts are well-established, those for noninvasive cysts are not defined. We used our experience with resected noninvasive mucinous neoplastic cysts to define recurrence rates and the optimal frequency of postoperative imaging follow-up.

METHODS: We reviewed the medical records of 134 patients with resected, pathologically confirmed noninvasive mucinous neoplasms between 2002 and 2012. Demographics, comorbidities, cyst characteristics, and recurrence were evaluated. Survival analysis was used to estimate the distribution of time to recurrence and regression models were used to investigate factors associated with recurrence.

RESULTS: Eighty-seven patients with intraductal papillary mucinous neoplasms (IPMNs) were compared with 47 patients with mucinous cystic neoplasms (MCNs). Those with MCNs were more often females (P = .001), significantly younger (P = .001), more symptomatic (P = .009), and had cysts more often located in the tail (P < .001). Median follow-up was 42 months. Recurrence rates for IPMNs were 0%, 5%, and 10% versus 0% for MCNs respectively at postoperative years 1, 2, and 3 (P = .014). On multivariable analysis, size >3 cm (P = .027), higher grade dysplasia (P = .043), and positive resection margins (P < .001) were significantly associated with recurrence.

CONCLUSION: Resected noninvasive IPMNs with moderate- or high-grade dysplasia and negative resection margins require imaging follow-up every 2 years, given the 16% overall recurrence rate. Although the follow-up interval for noninvasive, low-grade, dysplastic IPMNs with negative margins could be lengthened, all noninvasive IPMNs having positive margins require yearly follow-up at the minimum. Resected noninvasive MCNs--irrespective of grade and margin status--do not require surveillance, although the development of branch duct-IPMNs in the remnant pancreas can be investigated in the long term at the discretion of the provider.