A review of mucinous cystic neoplasms of the pancreas defined by ovarian-type stroma: clinicopathological features of 344 patients.

INTRODUCTION

Despite formal definitions of mucinous cystic neoplasms (MCNs) and intraductal papillary neoplasms (IPMNs) by the World Health Organization (WHO) and Armed Forces Institute of Pathology (AFIP), several controversies with regard to MCNs remain. The aim of this review was to determine the clinicopathological features of MCNs defined by ovarian-type stroma (OS) as proposed by the WHO and AFIP and to compare them with MCNs defined by less stringent criteria.

METHODS

A MEDLINE search was conducted to identify English-language articles on pancreatic MCNs from 1996 to 2005. Twenty-five studies were identified. The studies were divided into 2 groups: group A included 10 studies with 344 patients whereby the presence of OS was a criteria for the diagnosis of MCNs, and group B, included 15 studies comprising 761 patients whereby the presence of OS was not mandatory for the diagnosis of MCNs.

RESULTS

Patients in group A (MCNs as defined by OS) were almost always female (99.7%), with a mean age of 47 (range, 18-95) years. MCNs were located predominantly in the body or tail of the pancreas (94.6%) and had a mean size of 8.7 cm (range, 0.6-35 cm); 76% were symptomatic, 6.8% demonstrated ductal communication, and 27% were malignant. At a mean follow-up of 57.5 (range, 1-264) months and 43 (range, 2-257) months after surgery, 97.9% of benign and 61.9% of malignant neoplasms were disease free, respectively. Patients in group B were older and had a higher proportion of males. Neoplasms were more evenly distributed in the pancreas, were smaller, communicated more frequently with the pancreatic duct, and were composed of a higher proportion of malignant tumors compared with group A. Their clinicopathological features were intermediate between those of group A and patients with IPMN.

CONCLUSION

Pancreatic MCNs with OS have unique and distinct clinicopathological features. MCNs should be defined by the presence of OS, as it is the most reliable way of distinguishing MCNs from IPMN. Adoption of "looser" criteria will result in misclassification of some IPMNs as MCNs.