This trial is a prospective, exploratory and descriptive study. The primary objective is to identify early diagnostic biomarkers in patients with TIPMP based on the analysis of Treg lymphocyte subpopulations and epigenetic signatures, and the secondary objective is to characterize the biological processes underlying the transformation of a pre-neoplastic lesion into established ADPC.

To meet the objectives of the study, patients will have blood samples taken at the time of their TIPMP monitoring, i.e. at inclusion, 6 months, 1 year and 2 years. If echo-endoscopy is performed during MRI monitoring of their disease, and a sample is taken as part of the treatment, a tumor sample and an intra-cystic fluid sample will be collected as part of the protocol.

Inclusion Criteria:

1. Age over 18
2. Patient with intermediate-risk or high-risk TIPMP according to the European Study Group on Cystic Tumours of the Pancreas (3)
3. Signed consent to participate
4. Affiliation with a social security scheme, or beneficiary of such a scheme.

Exclusion Criteria:

1. Pregnant or breast-feeding woman
2. Person in an emergency situation or unable to give consent.
3. Adult subject to a legal protection measure (adult under guardianship, curatorship or safeguard of justice),
4. Unable to undergo medical follow-up for geographical, social or psychological reasons.
5. contraindication to MRI.