Participants not undergoing surgery will be assigned to the "Clinical Follow-up" study group. Blood, stool, pancreatic juice and cyst fluid collection will be done as per protocol. All participants in the Clinical Follow-up group will be contacted yearly for a telephone interview until they undergo surgery, die, receive a diagnosis that excludes them from the study, or for 5 years, and interval medical records will be obtained and reviewed. During follow-up results of clinically indicated follow-up imaging studies will be abstracted

Participants scheduled for surgical resection after their initial clinical evaluation will be assigned to the "Immediate Surgery" study group. Blood, stool, pancreatic juice and cyst fluid collection will be done as per protocol. Participants in the Immediate Surgery group will be followed until the surgical pathology of their pancreatic cyst is known.

Blood and stool will be collected at baseline from all study participants. Those in the Immediate Surgery group may undergo endoscopic pancreatic juice collection before surgery, either at the time of a clinically indicated endoscopic ultrasound (EUS) exam or during an optional pre-operative research endoscopy. Pancreatic cyst fluid will also be obtained from all participants in the Immediate Surgery group, either at the time of surgery, or during a clinically indicated preoperative EUS FNA procedure, or both. Pancreatic juice and cyst fluid will be collected opportunistically from participants in the Clinical Follow-up group who undergo a clinically indicated EUS, EUS FNA, or endoscopy exam.

Number of biospecimens collected

To validate the diagnostic accuracy of cyst fluid methylated DNA marker (MDM) assays for detection of HGD and cancer in pancreatic cysts undergoing surgical resection

To evaluate the performance of cyst fluid MDM assays for predicting development of HGD or cancer during 3-year follow-up in study patients who are initially managed non-operatively