Su1499 Creation of a Prediction Tool (M-PACT) to Accurately Identify Premalignant and Malignant Cysts in Patients Undergoing Endoscopic Ultrasound (EUS) for Evaluation of Pancreatic Cystic Lesions: Results From a Large Multicenter Cohort

Abstract

Introduction: The nature of pancreatic cysts often remains uncertain, despite several tests, resulting in unoptimal management for patients. nCLE is an imaging technique, enabling microscopic observation of solid organs, in vivo and in real-time, during an EUS-FNA procedure. This technique could potentially provide useful information to establish a differential diagnosis between mucinous and non mucinous neoplasms. A recent study, INSPECT, described nCLE criteria for the characterization of intraductal papillary mucinous neoplasms (IPMN). Further descriptions were needed to identify nCLE criteria for the characterization of mucinous cystadenomas neoplasms (MCN) and non mucinous lesions. A prospective multicenter French study (CONTACT) aims at assessing the yield of nCLE for the diagnosis of pancreatic cystic tumors. Interim results presented criteria specific of serous cystadenomas (SCA). However, nCLE criteria for the characterization of MCN are still unknown. Materials and methods: Over 10 months, 31 patients without chronic pancreatitis and with a lonely pancreatic cyst > 2 cm large were enrolled. Following EUS examination, the AQ-Flex 19 miniprobe was introduced in a 19G needle and real-time video sequences of the cyst wall were recorded. Intracystic fluid obtained was analyzed. Final diagnosis of MCN (n=6) was based on surgery. The other lesions were considered as IPMN (n=5), pseudocysts (n=7) and SCA (n=13) on pathological consideration or expert consensus. Four gastroenterologists and two pathologists, unblinded to the final diagnosis studied the 31 nCLE videos records and compared their findings to the pathological specimen. Results: A particular pattern was furtively and recurrently seen in sequences acquired in three of the MCN lesions: an epithelial border lined the cyst wall, with or without deep blood vessels, and without papillary organization. These features were only observed in MCN sequences. These criteria correlate with the histological structure of those tumors that are characterized by a tall columnar mucin-producing epithelium underlined by a thick fibrous tissue with pseudo-ovarian stroma and vessels. Conclusions: The mucinous columnar epithelial border of MCN can be highlighted by nCLE. The validation of this criterion by an external group is undergoing and results will be available by the beginning of 2014. If proven to be accurate, this new sign might be useful for the diagnosis of mucinous cystadenoma neoplasms.