Mucinous cystadenomas are exocrine epithelial tumors of the pancreas.  Although uncommon, most occur in elderly women, and are usually found in the tail or body of the pancreas.  Half of these tumors communicate with the pancreatic duct system.  They are well-encapsulated with a thick fibrous wall, and a multilocular internal structure.  The cysts are lined by mucinous columnar epithelium with papillary proliferation, which show mild, moderate, or severe cellular atypia.  Indications of malignancy include irregular outline of the cyst wall with tissue projecting into the lumen.  Other signs of malignancy include invasion of adjacent structures and metastases to the liver or lymph nodes.  In every new case of a pancreatic pseudocyst, the diagnosis of cystic pancreatic neoplasm should also be considered, especially if there are no known causes.

   Clinical symptoms develop insidiously, and laboratory studies provide limited assistance.  On US or CT, mucinous cystadenomas appear as unilocular or multilocular neoplasms, with internal sepation, and nodular tumor excrescences.  Calcifications are occasionally present in the periphery of the tumor.  The tumor surface is smooth, with a thick wall that may contain calcification.  ERCP shows ductal encasement or filling of an irregular cystic space (in cases of communicating cystadenomas).  Endoscopic US is the most sensitive technique for the characterization of cystic neoplasms.