Role of endoscopic ultrasound-guided fine-needle aspiration in the diagnosis of solid pancreatic and peripancreatic lesions: is onsite cytopathology necessary?

The reported median diagnostic yield from endoscopic ultrasound (EUS) fine-needle aspiration (FNA) cytology is 78% (range 39–93%). The aim of this study is to describe a single-centre experience in the diagnostic work-up of solid pancreatic and peripancreatic masses without the benefit of an onsite cytopathologist. In a consecutive series of 429 EUS examinations performed over a 12-month period by a single operator, 108 were on non-cystic pancreatic or biliary lesions. Data were collected prospectively and the accuracy of FNA was assessed retrospectively using either surgery or repeat imaging as the benchmark in the presence or absence of malignancy. Of the 108 FNAs, 102 (94%) were diagnostic, four were falsely negative (FN) and two were atypical and considered equivocal. There were 78 pancreatic lesions, of which 65 were true positives (TP), 11 true negatives (TN) and two FN, giving an overall accuracy of 97% (76/78). Of nine periampullary lesions, two were TP, six were TN and one was FN, giving an overall accuracy of 89% (8/9). The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of EUS-FNA for pancreatic and periampullary lesions combined were 96%, 100%, 100% [95% confidence interval (CI) 95–100%], 85% (95% CI 62–97%) and 97%, respectively. There were 21 bile duct lesions, of which 10 were TP, eight TN, two atypical and one FN, giving an overall accuracy of 86% (18/21). The sensitivity, specificity, PPV, NPV and accuracy of EUS-FNA for biliary lesions were 91%, 100%, 100% (95% CI 69–100%), 91% (95% CI 59–100%) and 95%, respectively. The diagnostic accuracy of EUS-FNA for pancreatic lesions in our series was 97% and the PPV for the three subgroups of lesion type was 100%; these figures are comparable with the best rates reported in the literature, despite the absence of onsite cytopathology. These rates are potentially a direct result of high-volume practice, dedicated endosonography and cytopathology. These results show that it is possible to achieve high rates of accuracy in places where logistical issues make it impossible to maintain a cytopathologist in the endoscopy suite. In addition, our results contribute to the limited, collective global experience on the effectiveness of EUS-FNA in periampullary and biliary lesions.