The Dilemma of the Dilated Main Pancreatic Duct in the Distal Pancreatic Remnant After Proximal Pancreatectomy for IPMN

Objective(s)A dilated main pancreatic duct in the distal remnant after proximal pancreatectomy for intraductal papillary mucinous neoplasms (IPMN) poses a diagnostic dilemma. We sought to determine parameters predictive of remnant main-duct IPMN and malignancy during surveillance.MethodsThree hundred seventeen patients underwent proximal pancreatectomy for IPMN (Indiana University, 1991-2016). Main-duct dilation included those >= 5mm or dilated on radiographic reports. Statistics compared groups using Student's T/Mann-Whitney U tests for continuous variables or chi-square/Fisher's exact test for categorical variables with P<0.05 considered significant.ResultsHigh-grade/invasive IPMN or adenocarcinoma at proximal pancreatectomy predicted malignant outcomes (100.0% malignant outcomes; P<0.001) in remnant surveillance. Low/moderate-grade lesions revealed benign outcomes at last surveillance regardless of duct diameter. Twenty of 21 patients undergoing distal remnant reoperation had a dilated main duct. Seven had main-duct IPMN on remnant pathology; these patients had greater mean maximum main-duct diameter prior to reoperation (9.5 vs 6.2mm, P=0.072), but this did not reach statistical significance. Several features showed high sensitivity/specificity for remnant main-duct IPMN.ConclusionsRemnant main-duct dilation after proximal pancreatectomy for IPMN remains a diagnostic dilemma. Several parameters show a promise in accurately diagnosing main-duct IPMN in the remnant.