Factors affecting the diagnostic value of liquid-based cytology by EUS-FNA in the diagnosis of pancreatic cystic neoplasms.

Background and Objectives: This study retrospectively evaluated the value of liquid-based cytology (LBC) alone for diagnosing pancreatic cystic neoplasms (PCNs) in a large sample and initially estimated factors that might affect LBC diagnostic ability. Methods: From April 2015 to October 2022, we prospectively enrolled 331 patients with suspected PCNs in our prospective database. Among them, 112 patients chosen to receive surgical resection were included. Only 96 patients who underwent EUS-guided cystic fluid LBC were finally studied. The diagnostic values of LBC for differentiating benign and malignant PCNs and subtypes of PCNs were evaluated. Results: There were 71 female and 25 male patients with a mean age of 47.6 ± 14.4 years. The median cyst size was 43.4 mm. The diagnostic accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of LBC for the differentiation of benign and malignant PCNs were 96.9%, 57.1%, 100%, 100%, and 96.7%, respectively. The overall diagnostic accuracy of LBC for specific cyst types was 33.3% (32/96). Cysts located in the pancreatic body/tail or with irregular shapes were more likely to obtain a definite LBC diagnosis. At the same time, age, sex, tumor size, cystic fluid viscosity, operation time, needle type, and presence of septation were not significantly different. Conclusion: Liquid-based cytology alone is useful for differentiating benign PCNs from malignant PCNs and can successfully characterize the PCN subtypes in one-third of patients. Pancreatic cystic neoplasms located in the body/tail or exhibiting irregular shapes are more likely to obtain a definite LBC diagnosis.