Endoscopic ultrasound for the evaluation of cystic lesions of the pancreas.

Although the exact prevalence of cystic pancreatic lesions is unknown, it is estimated to be around 1% of the general population based on large scale observational imaging studies [1]. While cystic pancreatic lesions are increasingly diagnosed due to the widespread use of cross-sectional imaging modalities like computed tomography (CT) and magnetic resonance imaging (MRI), it is not known if this reflects a true increase in incidence [1]. Inflammatory pseudocysts constitute about 75% of pancreatic cysts but are not classified as true cystic pancreatic lesions since they are non-epithelial inflammatory fluid collections associated with acute or chronic pancreatitis [2]. About 15% of cystic pancreatic lesions can be classified as cystic neoplasms that require further evaluation and monitoring due to risk of progression to malignancy [1, 3]. Based on surgical pathology, cystic pancreatic lesions are classified by the type of epithelium lining the cyst. These include serous cystadenomas, intraductal papillary mucinous neoplasms (IPMN), mucinous cystadenomas, mucinous cystadenocarcinomas, solid pseudopapillary tumors and few other rare types [4]. Despite being the most common modality to identify cystic pancreatic lesions, cross-sectional imaging plays a variable role in characterizing these lesions. Endoscopic ultrasound (EUS) provides real-time high resolution images of cystic pancreatic lesions with morphological details. The combination of fine-needle aspiration (FNA) cytology with the other recently available diagnostic markers has further increased its diagnostic accuracy. In this review, we describe the role of EUS in the diagnosis of commonly encountered cystic pancreatic lesions and review the management options for practicing clinicians.