Intraoperative irrigation cytology of the remnant pancreas to detect remnant distinct pancreatic ductal adenocarcinoma in patients with intraductal papillary mucinous neoplasm undergoing partial pancreatectomy

Background. Patients with intraductal papillary mucinous neoplasm (IPMN) of the pancreas may have concomitant distinct pancreatic ductal adenocarcinoma (PDAC). We evaluated the safety and usefulness of intraoperative irrigation cytology of the remnant pancreas (IICP) during pancreatectomy to detect remnant distinct PDAC in patients with IPMN. Methods. The records of all 48 patients with IPMN who underwent IICP during partial pancreatectomy at our institution from April 2007 to March 2012 were reviewed retrospectively. After division of the pancreas, a 4-French tube was inserted into the main pancreatic duct of the remnant pancreas from the cut edge, and fluid for cytologic examination was obtained by saline irrigation through the tube. If the third IICP was positive, patients underwent additional pancreatic resection. Clinical and pathologic outcomes were evaluated. Results. The third IICP was positive in 5 patients. Postoperative pathologic examination showed that these patients all had remnant distinct PDAC in the additionally resected specimen, which was not detectable on preoperative imaging examination or on intraoperative macroscopic examination, ultrasonography, or palpation. This PDAC was stage 0 in 4 patients and stage III in 1 patient. No procedure-related complications were observed. One patient developed peritoneal metastasis after 10 months, 1 developed liver metastasis after 20 months, and 1 developed PDAC in the remnant pancreas after 24 months. Conclusion. IICP seems to be a safe and useful method for detection of early stage PDAC concomitant with IPMN that cannot be detected by preoperative imaging or intraoperative examination.