Incidental pancreatic cysts: do we really know what we are watching?

BACKGROUND Most cystic neoplasms of the pancreas (CNPs) are incidentally discovered. Their management continues to be debated and preoperative diagnosis is often inaccurate. METHODS Retrospective review of 330 patients with incidentally discovered CNPs. Preoperative and final histological diagnoses were correlated. RESULTS 41% (136/330) of patients were operated on at diagnosis. 50 patients underwent resection for a presumed branch-duct (Bd) intraductal papillary mucinous neoplasm (IPMN), which was confirmed in only 64% (32/50); of the remaining patients, 20% had main-duct involvement. Mucinous cystic neoplasm was the preoperative diagnosis in 30/136 patients, histologic examination was confirmatory in only 60% (18/30). Most lesions presumed to be main-duct or combined IPMNs or serous cystadenomas were confirmed as such after resection (15/16 and 11/12, respectively). Multifocality was not only associated with Bd-IPMN, and 5% of all cysts were non-neoplastic. Overall, in only 68% of cases did the preoperative and histological diagnoses match. CONCLUSIONS In an experienced, high-volume center, preoperative diagnosis was incorrect in one-third of incidentally discovered CNPs who underwent resection. Of particular concern, 20% of presumed Bd-IPMN had a main-duct component. Conversely, 5% of resected cysts were not even neoplastic. Clearly, better diagnostic methods are needed to aid in formulating appropriate treatment strategies.