Accuracy and other quality indicators of solid pancreatic mass endoscopic ultrasound-guided fine needle aspiration and biopsy in two academic endoscopy centers

Background and aims Endoscopic ultrasound fine-needle aspiration/biopsy (EUS-FNA/FNB) is highly accurate, but discrepancies between cytological and surgical diagnoses are still observed. We aimed to determine its accuracy and monitor quality indicators in our facilities. Patients and methods We performed a retrospective review of all cases of pancreatic solid lesions evaluated by EUS-FNA/FNB, between July 2015 and June 2018, in two centers. Cytological and surgical findings were categorized into five groups: benign, malignant, suspect of malignancy, undetermined and insufficient for diagnosis. Final diagnosis was based on surgical diagnosis and, in patients who did not undergo surgery, on clinical outcome after 6 months follow-up. Results Altogether, 142 patients were included. FNA was the preferred tissue acquisition method (88%), with a predilection for the FNA 22G needle (57%). Cytology was insufficient for diagnosis in 2 cases, therefore a full diagnostic sample was available in 98.6% of the patients (>90%, ESGE target). Fifty-five (38.7%) patients underwent surgery. In term of cancer diagnosis, comparison with final surgical pathology (n=55) revealed 89% true positives, 5.5% true negatives, 3.6% false positives and 1.8% false negatives. When combining surgical diagnosis and clinical outcomes together, EUS-guided sampling sensitivity was 97.4% (92.5-99.5), specificity was 92.3% (74.9-99.1), positive predictive value was 98.2% (93.6- 99.5), negative predictive value was 88.9% (72.3-96.1) and accuracy was 96.4% (91.9-98.8). Post-procedural acute pancreatitis was reported in 2 patients (1.4%). Conclusions These results reveal a performance for diagnostic tissue sampling well above the ESGE proposed target standard. Also, the uncommon high specificity illustrates the determining role of the pathologist's final interpretation and diagnosis.