Side-branch intraductal papillary mucinous neoplasms of the pancreas: outcome of MR imaging surveillance over a 10 years follow-up

Abstract

Purpose: To evaluate the outcome of a MR imaging procotol in assessing the evolution of individuals with branch duct - intraductal papillary mucinous neoplasms (BD-IPMN) without worrisome features (WF) and/or high risk stigmata (HRS) at the time of the diagnosis in a follow-up period of at least 10 years.

Material and methods: A retrospective revision of a prospectively collected radiological database including a total number of 600 patients who were investigated and diagnosed with "presumed" diagnosis of BD-IPMN at MRI/MRCP at our Department since 2008 was performed. Inclusion criteria were: 1) absence of worrisome features and/or high-risk stigmata at the time of diagnosis (baseline); 2) a radiological follow-up with abdominal MRI/MRCP of at least 10 years. Changes in cysts size, development of WF, HRS and pancreatic cancer, and any other modification during the follow-up were retrospectively analysed by two observers in consensus.

Results: Sixty-nine patients fulfilled all the inclusion criteria. During surveillance, the cysts remained dimensionally unchanged or slightly reduced in size in 26.2% and 4.3% of cases respectively, whereas cyst enlargement was demonstrated in 69.5% of cases. Median annual growth rate was of 0.97 ± 0.87 mm/yr (range 0.13-5.0). WF and HRS developed in 10/69 (14.5%) and 3/69 (4.3%) cases, respectively. The incidence of pancreatic cancer in patients with BD-IPMN was 2.9%.

Conclusion: Our data confirm the low risk of pancreatic cancer development in patients with BD-IPMN, thus justifying an imaging follow-up. Worrisome features and high-risk stigmata were promptly identified during the follow-up, supporting the utility of our surveillance MR imaging protocol.

Keywords: Branch duct - intraductal papillary mucinous neoplasms (BD-IPMN); High-risk stigmata; Magnetic resonance cholangiopancreatography (MRCP); Pancreatic cancer; Worrisome features.

Fig. 1

a: Patient with BD-IPMN without any WF or HRS and regular Wirsung caliber at baseline MRCP; 1b: After 8 years of follow-up, MRCP shows segmental dilation of Wirsung duct measuring 7 mm at the level of the pancreatic tail (WF), associated to a diffuse increase in cysts size.

Fig. 2

a: Patient with BD-IPMN without any WF or HRS and regular Wirsung caliber at baseline MRCP; 2b: After 4 years of follow-up, MRCP well exhibits a diffuse dilation of the Wirsung duct with maximum diameter of 11 mm (HRS), associated to a diffuse increase in cysts size.

Fig. 3

a-c: Patient with BD-IPMN without any WF or HRS at the baseline; 3d-g: After 8 years of follow-up, an enhanced solid lesion (red arrows) developed (3d-f) with restriction of diffusivity (3f) at the level of pancreatic body-tail. An increase in cysts size is also observed on MRCP (3 g). Patient underwent surgery with final histopathological diagnosis of PC.

Fig. 4

The comparison between surgery and diameter of Wirsung duct showed that patients with Wirsung’s diameter less than or equal to 5 mm were associated with a significant decreased risk of surgical procedure, unlike the other group of patients with a Wirsung caliber greater than 5 mm (p = 0.003; odds ratio (OR) = 13.5)