Live and learn: unexpected benign disease after pancreaticoduodenectomy for presumed malignancy.

This study examines the incidence of unexpected benign (UB) disease in patients undergoing pancreaticoduodenectomy (PD) for suspected malignancy and investigates preoperative factors that may help differentiate benign from malignant disease. A retrospective analysis was conducted on consecutive patients who underwent PD for suspected periampullary or pancreatic malignancy (2011-2022). Demographic data, imaging findings, tumor markers, and postoperative outcomes were assessed, with comparison between UB and confirmed malignancy (CM) cases. UB disease accounted for 2.5% of PDs (16 patients). The median Ca19.9 level in UB group was 10.1 U/mL, with 25% above 37 U/mL. None of the six UB patients with a double duct sign had elevated Ca19.9. In contrast, 59.9% of CM patients had Ca19.9 > 37 U/mL (p = 0.005), confirming an independent predictor of malignancy (p = 0.001). CM patients required more preoperative biliary stenting than UB (57.3% vs. 31.5%, p = 0.038). UB patients had higher reoperation rates (37.5% vs. 9.3%, p = 0.001) then CM, but shared similar mortality rates (p = 0.106). UB disease after PD was infrequent and lower than prior reports (5-10%). Elevated Ca19.9 levels and the need for preoperative biliary stenting are predictor of malignancy. A multidisciplinary team approach with critical imaging assessment is crucial for improve diagnosis and minimize unnecessary resections.