Natural history of intraductal papillary mucinous neoplasm of pancreas during surveillance: focusing on cyst growth and manifestation of worrisome features

Abstract

Background: To evaluate the natural history of branch-duct intraductal papillary mucinous neoplasms (BD-IPMN) of the pancreas under surveillance and to recommend optimal follow up intervals and duration.

Methods: We included only patients whose imaging studies showed classical features of BD-IPMN, and conducted follow-up periods of at least 3 years. We reviewed radiologic and pathologic findings, and performed linear and binary logistic regressions to estimate cyst growth.

Results: We identified 1,369 patients diagnosed with BD-IPMN. The median annual growth rate of the cyst was 0.6 mm over a median follow-up time of 61 months. During surveillance, 46 patients (3.4%) underwent surgery due to disease progression after a median follow-up time (in this group) of 62 months. Worrisome features were observed in 171 patients (12.5%) during surveillance, including cyst size >3 cm (n=47, 3.4%), cyst wall thickening (n=51, 3.7%), main pancreatic duct (MPD) dilatation (n=78, 5.7%) and mural nodule (n=43, 3.1%). Along with annual cyst growth rate, incidences of MPD dilatation, cyst wall thickening and mural nodules were related to initial sizes of cysts at detection (P<0.001).

Conclusion: Most BD-IPMN appear indolent, but some exhibit rapid growth and progression. Therefore, surveillance protocols should be individualized with regards to the natural history of BD-IPMNs focusing on initial cyst size and growth rate.