Appropriate Interval for Imaging Follow-up of Small Simple Pancreatic Cysts

The frequency at which patients should undergo follow-up imaging of small pancreatic cysts is problematic because different medical societies have different follow-up guidelines.

To determine whether short-term follow-up of small pancreatic cysts is necessary to detect pancreatic cancer or cystic neoplasia.

We retrospectively reviewed all abdominal magnetic resonance imaging (MRI) studies obtained in a geographically isolated health maintenance organization between January 1, 2012, and December 31, 2014, looking for pancreatic cysts. For each patient with one or more simple cysts, we recorded the size of the largest cyst. For patients with cysts, all their other computed tomography and MRI studies were reviewed to determine any change in size or morphology. The electronic medical record of every patient who underwent MRI was reviewed to determine development of pancreatic cancer.

Change in cyst size on images.

Of 1946 patients, 342 were found to have at least 1 pancreatic cyst. A total of 228 patients had additional imaging from which to determine rates of change. The mean rate (standard deviation) of change for these cysts was 0.1 ± 2.0 mm/y. None of those cysts measuring 2 cm or smaller on MRI grew more than 5 mm in 2 years.

Our data validate the clinical efficacy of obtaining follow-up imaging no sooner than 24 months after the initial detection of a simple pancreatic cyst 2 cm or smaller. Patients with cysts are more likely to have pancreatic cancer, but earlier follow-up imaging would not change their diagnosis of pancreatic cancer.