This study focuses on pancreatic cysts, especially malignant pancreatic cysts. The primary hypothesis of the study is that using nCLE in addition to EUS-FNA and tissue sampling allows better characterization of pancreatic cysts and improves appropriate therapeutic decision-making. For physicians, integrating nCLE into the diagnostic algorithm of pancreatic cysts could impact patient management by: Ruling out malignancy for patients with benign appearing nCLE images. Characterizing more malignant tumors in the pancreas.

1. Medical background: Pancreatic cysts are quite rare, but are being increasingly recognized due to the expanding use of cross-sectional imaging. They are classified into three main classes: pseudocysts, serous cysts and mucinous cystic neoplasms. Either intraductal papillary mucinous neoplasm (IPMN) or mucinous cyst adenomas / mucinous cystadenocarcinoma(MCN) Mucinous cystic neoplasms are considered to be malignant or pre-malignant and are considered for surgical resection, whereas pseudocysts and serous cysts are considered benign and with a low potential for malignancy. Pseudocysts and serous cysts are usually only considered for surgical resection when symptomatic or enlarging.

2. Clinical background:

   2.1. Endoscopic Ultrasound (EUS) is the diagnostic method of choice when a pancreatic lesion is found incidentally on cross-sectional imaging. Endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) is a procedure where a target tissue in proximity to the GI tract is biopsied using a fine needle guided in real time by an ultrasound probe fixed at the tip of an endoscope. It may therefore be applied to pancreatic lesions, or lymph nodes examination.

   2.2. The principle of needle-based Confocal Laser Endomicroscopy (nCLE) is to image organs within or adjacent to the GI tracts with a miniprobe inserted through an endoscopic needle. The fundamental technology as well as the principle of operation of nCLE are substantially similar to pCLE.

3. Clinical evidence: Previous studies enabled to define interpretation criteria on the micro-structure of benign pancreatic cysts. Less data is available on malignant pancreatic cysts, except for a few images done in a pilot study of identification of pancreatic cystic neoplasms.

4. Objectives:

   4.1 The primary objective of the study is to assess the diagnostic performance of the Cellvizio nCLE system in diagnosing pancreatic cysts, when associated with other diagnostic information.

   4.2 The secondary objectives are to assess the potential impact of the Cellvizio nCLE system on patient management and validate the interpretation classification criteria that were created during the previous studies.

5. Design:

This study will be conducted in a single center in China.

Inclusion Criteria:

• Male or female > 18 years of age.
• Patient indicated for a first EUS-FNA for a pancreatic cyst or
• Patients who had previous non-diagnostic tissue sampling taken during a previous EUS-FNA for pancreatic cyst more than three months ago.
• Patient with known pancreatic cyst detected at cross-sectional imaging
• Willing and able to comply with study procedures and provide written informed consent to participate in the study.

Exclusion Criteria:

• Subjects for whom EUS-FNA procedures are contraindicated
• Known allergy to fluorescein dye
• If female, pregnant based on a positive hCG serum or an in vitro diagnostic test result or breast-feeding