菅野 敦

BACKGROUND: Intraductal papillary mucinous neoplasms (IPMNs) are classified into three epithelial types with distinct biological behaviors. However, their effects on the postoperative outcomes remain unclear. METHODS: This multicenter retrospective study included 556 patients with IPMNs who underwent surgical resection. The epithelial types were categorized into the gastric (n = 323), intestinal (n = 160), and pancreatobiliary (n = 73) types. Their associations with the development of extrapancreatic lesions; remnant high-risk lesions (HRLs), including metachronous pancreatic ductal adenocarcinoma (PDAC); and disease-specific survival (DSS) were analyzed. RESULTS: Fifty-one patients (9.2%) developed extrapancreatic lesions. The 10-year cumulative incidence rates for the gastric, intestinal, and pancreatobiliary types were 9.3%, 9.1%, and 32.0%, respectively (P < 0.001). Multivariate analysis identified invasive carcinoma, the gastric, and pancreatobiliary types as independent predictors. Among 516 patients who did not undergo total pancreatectomy, 40 (7.8%) and 13 (2.5%) developed HRLs and metachronous PDAC, respectively. The 10-year cumulative incidence rates of HRLs and metachronous PDAC for the gastric, intestinal, and pancreatobiliary types were 7.0%, 16.2%, and 37.2% and 1.8%, 3.7%, and 22.7%, respectively (P = 0.001 and P = 0.012). In multivariate analysis, the pancreatobiliary type was an independent predictor of metachronous PDAC. Five-year DSS rates for the gastric, intestinal, and pancreatobiliary types were 92.5%, 96.0%, and 76.1% (P < 0.001), respectively. Multivariate analysis identified invasive carcinoma, the gastric, and pancreatobiliary types as independent prognostic factors for DSS. CONCLUSIONS: IPMN epithelial type can independently affect postoperative outcomes. In particular, the pancreatobiliary type has significant impact on the development of metachronous PDAC. Therefore, postoperative surveillance should be tailored according to the epithelial type.

A 50-year-old man was diagnosed with type 1 autoimmune pancreatitis (AIP) following endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) and a histopathological examination. After six months of untreated follow-up, the serum IgG4 level decreased, and the diffuse pancreatic enlargement improved; however, a pancreatic head mass became apparent. EUS-FNA of this mass revealed pancreatic ductal adenocarcinoma (PDAC) with IgG4-positive plasma cells. In addition, the resected specimen revealed PDAC, without any features of AIP. After pancreatoduodenectomy, AIP did not recur. The development of AIP in this case could be related to paraneoplastic syndrome.