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

Abstract

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.

Fig. 1

Magnetic resonance cholangiopancreatography of a 64-year-old female with an incidentally discovered cystic lesion at the uncinate process of the pancreas. The lesion measured 2.7 cm and had no associated nodules; the rest of the pancreas was unremarkable. A presumed diagnosis of Bd-IPMN was made. Because of recent onset of diabetes, and a positive family history for pancreatic cancer, the patient underwent a Whipple's resection. Final diagnosis was combined main-duct and Bd-IPMNs.

Fig. 2

CT scan from a 67-year-old female with an incidentally discovered heterogeneous cystic lesion at the tail of the pancreas measuring 5.2 cm, and with internal calcium deposits. The patient was operated on with a preoperative diagnosis of an MCN, but the final pathology revealed a cystic neuroendocrine neoplasm.

Fig. 3

Accuracy of preoperative diagnosis in 125 incidentally discovered cysts resected at presentation. ∗ Includes 8 cystic endocrine neoplasms, 4 solid pseudopapillary neoplasms, and 5 with various other diagnoses. 11 patients did not have a specific preoperative diagnosis.

Fig. 4

Reformatted CT images from a 46-year-old female with the incidental discovery of multiple pancreatic cysts during the evaluation of non-specific lower abdominal pain. This was presumed to be multifocal Bd-IPMN or combined IPMN. The suspicion of an associated nodule, and a mildly dilated pancreatic duct to 6 mm, prompted an operation. The final pathological diagnosis was multifocal non-neoplastic cysts.