15 - Endoscopic Ultrasonography in the Evaluation of Pancreatic Cysts

Abstract

Pancreatic cysts are an increasingly recognized clinical entity, found in up to 13% of patients undergoing magnetic resonance imaging (MRI) with no symptoms or history of pancreatic disease. The differential diagnosis of pancreatic cystic lesions is wide; the majority of these lesions are benign, but detection of mucinous neoplasms (intraductal papillary mucinous neoplasms [IPMNs] and mucinous cystic neoplasms [MCNs]) is important because these cysts may be malignant or have malignant potential. Pancreatic cysts thus represent an important and increasing disease burden and pose a difficult diagnostic and management problem; that is, how to accurately predict which lesions contain malignancy and require resection versus those that can be followed safely by interval imaging or require no further follow-up. Despite advances in computed tomography (CT) and MRI, the ability of cross-sectional modalities to identify the exact nature of a cyst remains limited. Endoscopic ultrasonography (EUS) is ideally suited to image pancreatic lesions because of its high resolution and ability to sample cystic lesions. The diagnostic accuracy of EUS based on morphology alone is limited. A combination of EUS features, fluid cytology, carcinoembryonic antigen (CEA) level, and mucin staining is used to differentiate pancreatic cysts. Fine-needle aspiration (FNA) of cystic lesions under antibiotic cover is safe, with low rates of bleeding, infection, and pancreatitis. Accurate diagnosis and management of pancreatic cystic lesions requires careful evaluation of the clinical setting, other imaging modalities, and multidisciplinary collaboration. This chapter discusses the different types of pancreatic cysts, their endosonographic features, and the role of FNA for cytologic and tumor marker analysis. A diagnostic approach to patients with pancreatic cysts is also described.