Hôpital Saint-Joseph, Service d’hépato-gastroentérologie et de pancréatologie, 26 boulevard de Louvain, 13008 Marseille
Pancreatic cystic tumours are common in the general population after 50 years (5-10%) and are most often discovered incidentally. It is important to differentiate between cystic tumours with a risk of cancer: IPMN, mucinous cystadenoma, solid and pseudopapillary pancreatic tumour; and cystic tumours with no or exceptional risk of cancer: serous cystadenoma, cystic lymphangioma, lymphoepithelial cyst. Furthermore, these pancreatic cystic tumours should be differentiated from benign cystic lesions such as pseudocyst, intestinal duplication or cystic dystrophy of duodenal wall in heterotopic pancreas. When the clinical context and radiological appearance do not allow a conclusion, EUS with FNA and analysis of the pancreatic cyst fluid is essential to optimize the diagnosis accuracy. Recent techniques such as confocal laser endomicroscopy and cyst wall biopsy, guided by EUS, would increase the accuracy of EUS compared to imaging. In addition, analyses of biochemical (CEA, amylase and glucose) and genetic (K-RAS, GNAS, VHL, CTNB1) cyst fluid have excellent sensitivity in differentiate mucinous from non-mucinous cystic tumours. When the diagnosis of mucinous pancreatic cystic tumour is documented, evaluation of its prognosis is essential in order to choose between surveillance and preventive pancreatic surgery. EUS has a major role to demonstrate morphological signs of poor prognosis. In addition, the presence of genetic mutations in the cystic fluid (SMAD4, CDKN2A, TP53, PIK3CA and/or PTEN) would associated with risk of malignant cyst. In conclusion, EUS with FNA, with analysis of the fluid and the cystic walls, is essential to improve the management of pancreatic cystic tumours.