Pancreatic juice cytology with immunohistochemistry to detect malignancy and histologic subtypes in patients with branch duct type intraductal papillary mucinous neoplasms of the pancreas

Background and Aims: The aim of this study was to elucidate the efficacy of pancreatic juice cytology with the cell-block method (CB-PJC) for the determination of surgery in patients with branch duct intraductal papillary mucinous neoplasm (BD-IPMN). Methods: In 138 patients with BD-IPMN from whom pancreatic juice was collected under ERCP for CB-PJC, we retrospectively evaluated the following: (1) the rate of successfully evaluated CB-PJC; (2) the ability of CB-PJC to diagnose malignancy and to identify pathologic subtypes in resected BD-IPMNs; (3) the rate of development into invasive cancer and progression of BD-IPMNs in patients with BD-IPMNs diagnosed as benignancy by CB-PJC; and (4) post-ERCP adverse events. Results: (1) The success rate of CB-PJC was 89.9%. (2) The sensitivity and specificity of CB-PJC for preoperative diagnosis of malignancy were 50% and 100%, respectively, with only hematoxylin and eosin staining, whereas they were 79% and 100%, respectively, by adding immunohistologic staining. The agreement rate of the preoperative subtypes by CB-PJC with the subtypes of resected specimens was 93%. (3) The onset of invasive cancer was not detected at all on imaging studies, whereas the progression of IPMN was detected in 14 patients. Multivariate analysis revealed the risk factor of progression to be non-gastric type. The cumulative 5-year progression rate in this group was 89%. (4) Post-ERCP pancreatitis developed in 13 patients (7.7%). Conclusions: The diagnostic efficacy of preoperative CB-PJC for malignant BD-IPMN was excellent. The results may suggest the feasibility of applying preoperative subtyping by CB-PJC for decisions as to whether surgery is indicated.