- Last Update On : 2013-01-27
Advances in imaging techniques have resulted in the detection of an increased number of previously undetectable pancreatic cysts. Some studies have estimated that approximately 1% of inpatients have pancreatic cysts, many of which are small and asymptomatic.
The majority of pancreatic cysts can be classified into 4 main categories: pseudocyst, intraductal papillary mucinous neoplasm (IPMN), mucinous cystic neoplasm (MCN), and serous cystadenomas. The risk of malignancy is low in pseudocysts and serous cystadenomas but may be higher in IPMN and MCN. The clinical dilemma is the identification of those cysts that require further evaluation and possible resection from those that have a low risk of malignancy and can be followed.
Many pancreatic cysts can be classified solely on the basis of clinical and radiologic data, while a minority may require additional tests on the cyst fluid. Cytologic assessment for mucin and abnormal cells, CEA and amylase are most often ordered.
CEA is generally undetectable or low in aspirates from pseudocysts. CEA is often helpful in separating mucinous cysts (IPMN and MCN) from nonmucinous cysts. Fluid from serous cystadenomas often has CEA values <5 ng/mL. IPMN and MCN produce fluid with increased CEA due to the mucinous ining of these cysts. In general, the higher the CEA value, the more likely the cyst is a mucinous cyst, with the associated risk of malignancy.
Amylase may be helpful in differentiating pseudocyst from serous cystadenoma. Cyst fluid amylase is most always substantially elevated in pseudocysts, with values often exceeding 1000 U/mL, but low in serous cystadenoma. IPMN have variable amylase levels since many communicate with the pancreatic ductal system.
Molecular testing for KRAS mutation may also by helpful in specific circumstances. The presence of KRAS mutation with allelic loss is associated with mucinous cystic tumors. The combination of KRAS mutation with CEA elevation appears to be more sensitive for detection of malignancy than either test alone.