Ybao Liu MD, PhD, Presenter: Nothing to Disclose

Fatih Akisik MD, Abstract Co-Author: Nothing to Disclose

Kumaresan Sandrasegaran MD, Abstract Co-Author: Nothing to Disclose

Temel Tirkes MD, Abstract Co-Author: Nothing to Disclose

Mark Tann MD, Abstract Co-Author: Nothing to Disclose

Jordan K. Swensson MD, Abstract Co-Author: Nothing to Disclose

Chang Hong Liang MD, Abstract Co-Author: Nothing to Disclose

Chen Lin PhD, Abstract Co-Author: Research Grant, Siemens AG

We wanted to evaluate if there is clinical value in  serial imaging exams  for side branch intraductal papillary mucinous neoplasm (SB-IPMN), by observing  the natural history of  these lesions using CT/MR imaging and ERCP/EUS data.

This retrospective HIPAA-compliant study was approved by the authors’ institutional review board, with waiver of informed consent. 327 patients (113 male, 214 female, mean age at time of first diagnosis, 65.95 years; range, 25-90 years) with SB-IPMN were followed up to 98 months with cross-sectional exams (CT, MRI or both) were enrolled in the study. All imaging exams, along with patients' EUS and ERCP data, were evaluated by analysis of cystic lesions including initial and final absolute sizes, absolute cyst growth rates, percentage size differences, and growth rate percentages. The differences in septation and the presence or absence of a mural nodule between CT, MRI and EUS were compared. Statistical analysis included the t test, analysis of variance (ANOVA), and McNemar test.

The mean follow up time was 40.5 months, ranging between 12 and 98 months. In the absence of a mural nodule or thick septa, no malignant tranformation was noted independent of size. Initial cyst sizes averaged 12 ± 9.0  mm with a range between 0 - 60 mm. At the end of follow up, cyst sizes averaged 14 ±10 mm.  Average cyst growth was 2 ± 7  mm. Smaller cysts, <10mm,  showed greater mean cyst growth rate  (30%) (P ＜.001) .  Cysts with septation and mural  nodules (malignant cysts) were more common in older patients 72 ±9.6 years. Comparing the benign and malignant lesion groups, malignant cysts had larger initial (29  ± 15 mm)  and final cyst sizes (36 ± 19 mm) (P ＜ .05), and had a higher cyst growth rate (30 ± 62% ) ( P= .02),

In side branch IPMNs smaller than 30 mm , without  mural nodules or septations,  we did not observe malignant tranformation on long-term follow up. Additionally,  increase of cyst size did not predict malignancy. Therefore, there may be no need to perform serial evaluation of this group.

If a SB-IPMN shows no mural nodule or septa , perhaps no further imaging  followup is indicated, as interval change in size without these features did not predict malignancy.

Liu, Y, Akisik, F, Sandrasegaran, K, Tirkes, T, Tann, M, Swensson, J, Liang, C, Lin, C, Risk Stratification of Side Branch Intraductal Papillary Mucinous Neoplasm of the Pancreas, Based on Long-term Follow Up Results.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14006839.html