Diagnostic Value of Cytology in Pancreatic Endoscopic Ultrasound-Guided Fine Needle Aspiration: Accuracy in Common Epithelial Pancreatobiliary Tumors and the Role of Cell Block Analysis.

Background & objective: Limited literature describes the accuracy of endoscopic ultrasonography-fine needle aspiration (EUS-FNA) cytology in various types of pancreatic epithelial tumors, and this underscores the usefulness of cell blocks, and highlights potential diagnostic pitfalls.

Methods: This study included 108 patients who underwent EUS-FNA pancreatobiliary cytology followed by surgery. Age, gender, tumor location, tumor size, presence or absence of a cell block, cytologic and pathologic diagnoses, and histologic tumor grade were recorded. Cytologic and pathologic slides were examined, and the cytologic accuracy was determined by comparing cytologic with the histopathologic results as the gold standard. Additionally, the impact of cell block on the cytologic accuracy was assessed.

Results: EUS-FNA cytology showed an overall accuracy of 80%, a sensitivity of 90%, and a false-positive rate below 1%. Pancreatic ductal adenocarcinomas (PDAs) accounted for 65% of cases, followed by neuroendocrine tumors (NETs), solid pseudopapillary neoplasms (SPNs), mucinous cystic neoplasms (MCNs), and chronic pancreatitis. Diagnostic accuracy was higher for PDA and SPN than for NET and MCN and significantly improved to 100% in cases with a cell block.

Conclusion: Combining pancreatobiliary cytology with a cell block significantly enhances diagnostic accuracy, reaching 100%. Moreover, poorly differentiated PDAs and well-differentiated organoid-type tumors, such as NETs and SPNs, demonstrate higher diagnostic accuracy.