Pancreatic Resection for Side-Branch Intraductal Papillary Mucinous Neoplasm (SB-IPMN): a Contemporary Single-Institution Experience

Background: Given the malignant potential of main duct intraductal papillary mucinous neoplasm (M-IPMN), surgical resection is generally indicated. With regard to side-branch intraductal papillary mucinous neoplasm (SB-IPMN), resection vs. observation is a topic of debate. Further review of SB-IPMN is necessary to clarify appropriate management. The primary focus of this project is to determine the incidence of malignant final pathology for patients undergoing surgery for isolated SB-IPMN with non-malignant fine-needle aspiration (FNA) cytology. We also sought to describe the relationship between factors considered in the international consensus guidelines and final pathologic outcome. Methods: The study is a retrospective review of all patients who underwent surgical resection for intraductal papillary mucinous neoplasm (IPMN) from 2002 to 2013 at our institution. Patients with a preoperative diagnosis of isolated SB-IPMN and FNA results for non-malignant cytology were selected among this surgical cohort for further analysis of preoperative clinical characteristics and outcomes. Results: A total of 137 patients undergoing resection for IPMN were identified. Of these, 81 patients (59 %) had a component of M-IPMN or invasive disease on FNA, leaving 66 (46 %) patients with SB-IPMN and non-malignant cytology. Invasive adenocarcinoma was found in 8/66 (12 %) patients and high-grade dysplasia (HGD) in 4/66 (8 %) patients. The mean [SD] diameter of benign SB-IPMN was 2.0 cm [1.1] (range 0.3–5.7) vs. that of HGD/invasive disease which was 3.1 cm [1.3] (range 1.5–6.0; P = 0.014). Of the 12 patients found to have HGD or invasive disease, symptoms, mural nodules, and septations were found in 7 (58 %), 5 (42 %), and 6 (50 %), respectively. Tumor staging were as follows: IA (2), IB (2), 2A (4), and 2B (1). Conclusion: With proper selection criteria, SB-IPMN is associated with a low rate of invasive pancreatic ductal adenocarcinoma at the time of resection. Nevertheless, given the demonstrated incidence of malignancy, appropriate operative candidates should undergo resection.