Prognostic value of mural nodules and their size in IPMN of the pancreas: high-volume center experience, systematic review and meta-analysis

Abstract

Background: Mural nodes (MN) are well-established predictors of malignancy in IPMN and are a major indication for surgery for Guidelines. Less is known about whether their size might play a role in risk assessment. Methods: A systematic review of the literature was carried out following the PRISMA statement. A meta-analysis was conducted on selected studies reporting MNs size and final IPMN pathology. The random effect model was adopted and the pooled SMD (standardized mean difference) obtained. The IPMN surgical series of a single high-volume Institution was retrospectively reviewed. Only patients with comprehensive data about MN at MRI were included in the study. Results: The systematic review included 70 studies. Overall, the presence of MN had a positive predictive value for malignancy of 60.1%. The meta-analysis carried out on the 7 studies considered as eligible suggested that the size of MN has a considerable effect in predicting malignancy in IPMNs, with a mean SMD of 0.79. Of 317 resected IPMNs at our Institution, 102 (32.1%) had a preoperative diagnosis of MN. MN is the only independent predictor of malignancy for both branch duct IPMN and for IPMN with main pancreatic duct involvement. Conclusion: The presence MN is a reliable predictor of malignancy in IPMNs. Contrast enhanced endoscopic ultrasound seems to be the best tool in characterizing MNs’ size obtaining the best accuracy in predicting malignancy. Further studies will have the aim to identify potential MN dimensional cut-offs.