Progression of pancreatic cystic lesions without any risk features is associated with initial cyst size and obesity.

The clinical significance of incidental pancreatic cystic lesions (PCLs) remains unclear in those which are not accompanied by worrisome features or high-risk stigmata. We aimed to investigate the natural course of PCLs without any risk features and examine the clinical factors associated with their progression.We conducted a retrospective cohort study of 427 patients with PCLs, which were incidentally detected by computed tomography between January 2003 and December 2012. Progression of PCLs without any risk features and the clinical factors associated with their progression were investigated. The length of time to significant growth was also evaluated.Ninety-four (22.0%) of the 427 patients had asymptomatic PCLs that showed significant growth after a median surveillance period of 5.3 years; approximately 27.7% of the patients showed significant size changes in the first 5 years, while the remaining 72.3% showed significant changes after 5 years. The cumulative rate of patients with significant growth was associated with initial cyst size and high body mass index. In the growth group, additional treatments were required for 12 patients, one of whom developed malignancy. Four patients in the stable group underwent additional treatment and showed no malignant change.One-fifth of the asymptomatic PCLs significantly increased in size after a long-term follow-up period, which was associated with initial cyst size and obesity. The size of PCLs mostly increased after 5 years; although the malignancy risk of PCLs was low, it was still a concern.