The benefits of the Papanicolaou Society of Cytopathology System for reporting pancreatobiliary cytology: A 2‐year review from a single academic institution

Abstract

Endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) is an essential tool in the diagnosis of pancreatic lesions. The aim of this study was to evaluate the diagnostic accuracy of cytology from EUS-FNA, to correlate the results with the corresponding histopathological diagnoses and to analyse the impact of retrospective assignment of the Papanicolaou Society of Cytopathology (PSC) reporting system categories. All pancreatic FNA specimens reported at the Royal Free Hospital during a 2-year period were retrospectively collected and assigned to the PSC system categories. Any available corresponding histological samples were assessed for concordance. In total, 236 cytology specimens from 223 patients were identified, of which 108 (45.8%) had corresponding histology samples. The main reason for cyto-histological discrepancy was sampling error. Interpretive error was identified in one case. Overall, sensitivity was 92.5%, specificity was 100%, diagnostic accuracy of cytology was 95%, false-positive rate was 0% and false-negative rate was 7.5%. The implementation of the new reporting system reduced the number of cases in the atypical category. All cases previously categorised as suspicious or malignant remained in the same category. EUS-FNA is an accurate method for evaluating pancreatobiliary lesions. The implementation of the Papanicolaou Society of Cytopathology diagnostic system enhances standardisation of the reporting terminology and reduces the number of samples in the non-standardised and equivocal atypical category.