Interobserver Agreement among Cytopathologists in False-Negative Cases by Cytological Diagnosis with Endoscopic Ultrasound-Guided Fine Needle Aspiration in Solid Pancreatic Lesions.

Introduction: Early detection and accurate pathological assessment are critical to improving prognosis of pancreatic cancer. EUS has been widely used in diagnosing pancreatic lesions and can obtain histological diagnosis by endoscopic ultrasound-guided fine needle aspiration (EUS-FNA). However, comprehensive assessment of the interobserver agreement (IOA) among cytopathologists evaluating EUS-FNA specimens is still limited. Therefore, this study evaluated IOA among cytopathologists for EUS-FNA specimens of solid pancreatic lesions, especially in false-negative cases of cytological diagnosis and analyzed the factors that influence cytological diagnosis of EUS-FNA so as to improve the diagnostic efficiency of EUS-FNA.

Methods: We retrieved EUS-FNA samples of pancreatic solid lesions from 2017 to 2021 and collected their clinical/cytological data. Two cytopathologists independently reviewed these cases using a quoted, novel standardized cytology scoring tool. Ultimately, we calculated IOA among cytopathologists and performed a binary logistic regression analysis to evaluate factors influencing the cytological diagnosis of EUS-FNA.

Results: 161 patients were included, and 60 cases with a clinical diagnosis of pancreatic cancer but a cytological diagnosis of benign and atypical constituted the false-negative group. IOAs for cytological diagnosis of overall patients and the false-negative group were in perfect/moderate agreement with Kendall's W values of 0.896 and 0.462, respectively. The number of diagnostic cells in the scoring tool had the highest level of agreement (κ = 0.721) for overall patients. There was at best moderate agreement on other quantity and quality parameters for both all cases and false-negative group. Logistic regression analysis showed the number of diagnostic cells (OR = 6.110, p < 0.05) and amount of blood (OR = 0.320, p < 0.05) could influence cytological diagnosis.

Conclusions: The false-negative rate of our study as high as 37.26% (60/161) is mainly related to strict standards of cytopathologists, and their ability to standardize pancreatic cytology is still improving. Suboptimal agreement among cytopathologists for cytological diagnosis and the number of diagnostic cells may be associated with the occurrence of false-negative diagnosis. Further regression analysis confirmed that the number of diagnostic cells and obscuring blood were important factors in cytological diagnosis. Therefore, refinement of cytological diagnostic criteria, standardization of specimen quality evaluation, and training of cytopathologists may improve the agreement of cytopathologists, thus improving the repeatability of cytological diagnosis and reducing the occurrence of false-negative events.