Cytology from Pancreatic Cysts Has Marginal Utility in Surgical Decision-Making

Background: Preoperative diagnosis of pancreatic cystic neoplasms is problematic. We evaluated our experience with endoscopic ultrasound (EUS) to determine the utility of fine-needle aspiration cytology (FNAC) in surgical decision-making. Methods: Patients evaluated for pancreatic cysts with EUS fine-needle aspiration (FNA) from 3/1996-10/2003 were included. Patients undergoing both preoperative EUS-FNA and pancreatic resection were identified. FNAC read as a mucinous cystic neoplasm (MCN), suspicious for neoplasia, or mucinous epithelial/atypical cells were classified as concerning. Cytology with no malignant cells was negative. FNAC read as indeterminate, atypical cells of undetermined significance, or possible contamination was nondiagnostic. Results: Of 95 patients evaluated with EUS FNAC, 29 underwent resection. On final pathology, 7/29 lesions (24%) were malignant [two neuroendocrine tumors, three adenocarcinomas, one invasive intraductal papillary mucinous neoplasm (IPMN), and one metastatic uterine tumor], 4/29 (14%) were benign (three serous cystadenomas and one chronic pancreatitis), and 18/29 (62%) were premalignant (ten MCNs and eight IPMNs). Seven patients had concerning FNAC. All seven harbored malignant or premalignant lesions. Nine patients had negative FNAC: three (33%) with benign lesions and six (67%) with premalignant lesions. Thirteen of the 29 patients (45%) had nondiagnostic FNAC with 12/13 (92%) harboring a malignant or premalignant lesion. Sensitivity, specificity, positive predictive value, and negative predictive value were 28%, 100%, 100%, and 18%, respectively. Conclusion: The decision to proceed with nonoperative management should not be based on a negative or nondiagnostic FNAC alone, as 67% of negative and 92% of nondiagnostic specimens were associated with malignant or premalignant pathology.