Study objective: To establish a long-term follow-up cohort of patients with IPMN, study the follow-up, clinical outcomes and prognostic factors of patients with IPMN, and provide a basis for clinical decisions and guidelines.

Study design: This is a real world, multicenter, prospective, observational cohort study

Baseline assessment will be conducted on IPMN patients who meet the inclusion conditions and are included in the study with informed consent, including: ① demographic characteristics (such as age, gender, etc.); ② Clinical features (such as symptoms, complications, past history, family history, living/eating habits); ③ Characteristics of laboratory indicators (such as pancreatic function, liver enzyme, bile duct enzyme, CA199, CEA in blood; CA199, CEA in cystic fluid, etc.); ④ Imaging features * (such as multiple or single lesions, diameter of cyst, whether there are mural nodules, diameter of main pancreatic duct, etc.); ⑤ Endoscopic ultrasound (EUS) features * (such as: cyst location, echo, maximum diameter, whether the cyst wall is thickened, wall nodules, the connection between the cyst and the main pancreatic duct, laser confocal endoscopy features, etc.); ⑥ Pathological information (cytology of cystic fluid; cytological smear of cystic lesion puncture, histopathology); ⑥ Molecular characteristics of cyst fluid (such as proteomics/mass spectrometry, new biomarkers, next generation sequencing (NGS), flora characteristics, etc.); ⑦ Treatment information (such as current medication, whether to have received endoscopic treatment, etc.).

The follow-up contents include: outpatient follow-up (symptoms, laboratory indicators; keeping peripheral blood samples) every six months;, imaging follow-up (including enhanced pancreatic MR and EUS imaging; the first pancreatic MRI follow-up was conducted 6 months after enrollment to determine the stability of the lesions) at baseline and every 12 months thereafter.

During the follow-up, if the patient died of various causes, the follow-up will be terminated; If enhanced nuclear magnetic resonance imaging or EUS imaging of the pancreas indicates worrisome features (WFs) or high-risk features (High risk stigmata, HRS), EUS-FNA ± nCLE should be performed (when performing EUS, perform contrast-enhanced ultrasonography on cystic lesions with mural nodules, and collect cystic fluid when puncturing some cystic lesions with sufficient volume).

If the cytological/histological pathological results of FNA indicate cancer or high grade dysplasia (HGD), or/and cystic fluid cytological results are positive, surgical treatment is recommended; If the FNA and cyst fluid cytology results are negative, the patients with WF will be followed up 6 months later, while the HRS patients will be followed up 3 months later (whether to accept EUS examination is decided jointly by the follow-up physician and the patient). It is suggested to review EUS-FNA ± nCLE according to the imaging results. If the patient was advised to receive surgical treatment due to IPMN, the follow-up was terminated.

Inclusion Criteria:

1. Age: 18 years old or above;
2. Diagnosis: Imaging examination showed the presence of intraductal papillary mucinous cystic tumor (IPMN) without high-risk features (including WF and HRS);
3. The patient or family members can understand the study protocol, are willing to participate in the study, and provide written informed consent.

Exclusion Criteria:

1. The patient's clinical, imaging and auxiliary examination characteristics conform to the surgical indications of the International Association of Pancreatic Diseases (IAP) 2018 guidelines, and the patient has no surgical contraindication;
2. Previous history of pancreatic malignant tumor;
3. There were the following worrisome features (WF) of IPMN found in the past examination: acute pancreatitis, cyst size ≥ 30mm, cyst wall thickening/strengthening, main pancreatic duct diameter of 5-9.9mm, non enhanced mural nodules, sudden change of main pancreatic duct diameter with distal pancreatic atrophy;
4. The following high risk features of IPMN (HRS) were found in the past: obstructive jaundice, enhanced mural nodules or related solid components, and main pancreatic duct>10mm;
5. The patient or family member could not understand the conditions and objectives of this study.

IPMN patients in Peking Union Medical College Hospital and other related research centers