Prior to the 1980s, pancreatic cysts were relatively uncommon and, when identified, were usually mucinous or serous neoplasms or tumors. The wider use of imaging technologies has led to more pancreatic cysts being found and a greater understanding of their character. Clinically, the challenge that imaging detection of asymptomatic pancreatic cysts present is that, while 95% are non-neoplastic, it is often difficult to distinguish neoplastic from non-neoplastic cysts. Estimates indicate that pancreatic cysts are found in 1% of general medical patients who undergo medical imaging for other reasons. Treatment options for pancreatic cysts are surgical resection, assessment by endoscopic ultrasonography with fine-needle aspiration and cyst fluid analysis, or regular monitoring for changes in cyst appearance with computer tomography and/or endoscopic ultrasonography. There are no well-accepted criteria that define cysts that are appropriate for resection, as knowledge of pancreatic cysts is still developing. Approximately 30 different kinds of pancreatic cysts are described in the medical literature; however, the cysts most commonly encountered in clinical practice are, in order of increasing malignant potential: pseudocysts; serous
cystadenomas; solid pseudopapillary neoplasms; intraductal papillary mucinous neoplasms; and mucinous cystic neoplasms. Following the identification of a pancreatic cyst by imaging, the first differential diagnostic step is to distinguish between a pseudocyst and a neoplastic cyst using a variety of clinical characteristics. Following elimination of a pseudocyst, many physicians try to distinguish between serous and mucinous cysts. The use of different radiological and endoscopic imaging modalities and molecular cyst fluid analysis of fine-needle aspirations are all useful in differential diagnosis of pancreatic cysts. Analysis of pancreatic cyst fluids has resulted in a number of nonmolecular markers being proposed, with carcinoembryonic antigen (CEA) levels being the most useful in helping to decide whether pancreatic cysts are mucinous or nonmucinous. This distinction is important because of the higher malignant potential of mucinous pancreatic cysts. For a proportion of pancreatic cysts, clinical and histological examinations do not provide a definite diagnosis; in these patients, molecular analysis of cyst fluids collected using fine-needle aspiration guided by endoscopic ultrasonography may be useful.