Mucinous cystic neoplasms of the pancreas: Imaging features and diagnosticdifficulties

AIMS: To review the imaging features of mucinous cystic neoplasms (MCNs) of the pancreas and to highlight difficulties in differentiating these lesion s from pancreatic pseudocysts. MATERIALS AND METHODS: The imaging investigations, case notes and histopath ology of 13 patients who underwent surgery for an MCN of the pancreas, were reviewed. RESULTS: An erroneous diagnosis of a pancreatic pseudocyst had been made in five of the 13 cases and in two patients cystenterostomy had been performe d, Only one patient had a documented history of acute pancreatitis although mildly elevated serum amylase levels were identified in a further five cas es. CT and US correctly diagnosed a cystic pancreatic mass in all 13 patien ts, however cross-sectional imaging features of neoplasia, such as septae, cyst wall calcification, focal thickening of the cyst wall and papillary pr ojections, were absent in five (38%) cases. Coexistent imaging features of chronic pancreatitis were present in five of the 13 patients and in six res ected specimens. Cyst wall calcification occurred only in malignant lesions and there was no relationship between cyst size and the degree of malignan cy. While ERCP, angiography, and percutaneous needle aspiration may provide additional information, the majority of these examinations were either unh elpful or even misleading, CONCLUSION: MCNs of the pancreas are frequently diagnosed and mismanaged as pancreatic pseudocysts with an associated increase in patient morbidity an d mortality, Diagnostic imaging can help to distinguish MCNs from pseudocys ts when there are features of neoplasia present, however, no imaging invest igation can reliably differentiate the two conditions in all cases. If clin ical doubt remains, it is preferable to err on the side of safety and eithe r employ a 'wait and watch' strategy or to resect a cystic pancreatic lesio n rather than drain a potentially malignant MCN. (C) 2000 The Royal College of Radiologists.