EUS in cystic lesions of the pancreas.

The differential diagnosis for cystic lesions of the pancreas is broad and the role of EUS is becoming more clearly defined. Pancreatic cysts may be inflammatory, such as pseudocysts, in which the cyst wall lacks an epithelium. Inflammatory cells line the fluid collection, which may often be located adjacent to an area of acute or chronic pancreatitis. Other types of pancreatic cysts may be broadly classified as benign or malignant. Benign cysts include serous cystadenomas (microcystic cystadenoma), lymphangioma, cystic teratoma, hemangioma, or paraganglioma. Malignant cysts include mucinous cystic neoplasms (mucinous cystadenoma or cystadenocarcinoma). These are lined by mucinous epithelium. Cystadenocarcinomas are believed to arise from cystadenomas. The latter are therefore considered premalignant. Other mucinous cystic lesions include mucinous ductal ectasia (MDE), now more correctly referred to as intraductal papillary mucinous tumor (IPMT). A rare form of islet cell tumor may include a cystic component, that is, cystic islet cell tumor. Occasionally, other neoplasms may be of mixed origin and are called solid cystic tumors.1 One possible etiology for mixed tumors is ossification of a cystic tumor.