Imaging Features to Distinguish Malignant and Benign Branch-Duct Type Intraductal Papillary Mucinous Neoplasms of the Pancreas

In Brief Objective: To systematically determine the imaging findings for distinguishing malignant and benign branch-duct type intraductal papillary mucinous neoplasms (BD-IPMNs), including mixed type, and their diagnostic value through meta-analysis of published studies. Background: Management of BD-IPMNs, including mixed type, largely relies on imaging findings. The current knowledge on imaging findings to distinguish malignant and benign BD-IPMNs has weak evidence and is mostly from scattered individual retrospective studies. Methods: Thorough literature search in Ovid-MEDLINE and EMBASE databases was conducted to identify studies where findings of computed tomography, magnetic resonance imaging, and endoscopic ultrasonography of BD-IPMNs with or without main pancreatic duct (MPD) dilatation were correlated with surgical/pathological findings. Review of 1128 article candidates, including full-text review of 102 articles, identified 23 eligible articles with a total of 1373 patients for meta-analysis. Dichotomous data regarding distinction between malignant and benign BD-IPMNs were pooled using random effects model to obtain the diagnostic odds ratios (DORs) and their 95% confidence intervals (CIs) of various individual imaging findings for diagnosing malignant BD-IPMN. Results: Presence of mural nodules revealed the highest pooled DOR (95% CI) of 6.0 (4.1–8.8) followed by MPD dilatation [3.4 (2.3–5.2)], thick septum/wall [unadjusted, 3.3 (1.5–6.9); publication bias-adjusted, 2.3 (0.9–5.5)], and cyst size greater than 3 cm [2.3 (1.5–3.5)]. Multilocularity and multiplicity of the cystic lesions did not reveal statistically significant association with malignancy. Conclusions: Presence of mural nodules should be regarded highly suspicious for malignancy warranting a surgical excision whereas cyst size greater than 3 cm, MPD dilatation (5–9 mm), or thick septum/wall may better be managed by careful observation and/or further evaluation. We aim to determine the imaging findings for differentiating malignant and benign BD-IPMNs (branch-duct type intraductal papillary mucinous neoplasms) and their diagnostic value through meta-analysis. Pooled diagnostic odds ratio with which to suggest malignant BD-IPMN was the highest for the presence of mural nodule, followed by main pancreatic duct dilatation, defined as diameter 5 to 7 mm, thick septum/wall, and cyst size greater than 3 cm.