Fine Needle Aspiration versus Fine Needle Biopsy of Biliopancreatic Lesions: Are They Really Opposing Techniques or Can They Be Complementary? Our Experience in a Large Cohort of Cases from a Single Institution

Introduction: Nowadays, endoscopic ultrasound (EUS)-guided fine needle aspiration (FNA), and fine needle biopsy (FNB) are considered the best procedures for the diagnosis of biliopancreatic lesions. These methods represent a milestone since they proved to be both safe for the patient and useful to achieve diagnostic material useful to plan the best treatment strategy. Objective: Since in the literature, a debate between cytology and histology supporters is still ongoing and the trend is changing in favor of FNB, we would like to present our experience about the diagnostic yield of FNA and FNB. The aim of our study is to highlight FNA versus FNB diagnostic role of biliopancreatic lesions, highlight advantages, and drawbacks of these procedures, and our view on these 2 procedures and whether they should still be considered complementary or opposing techniques. Methods: We retrospectively reviewed our hospital series of 469 EUS diagnostics procedures of biliopancreatic lesions performed in 419 patients, between 2015 and 2019. Results: The overall adequacy rates of FNA and FNB were, respectively, 98.9 and 100%. Stratifying cases according to anatomic location of the mass (pancreas vs. biliary system), we detected 168 malignancies out of 349 pancreatic lesions (168/349; 48.1%), while biliary system cases positive for malignancy represented 33.8% (23/68 cases) (p value = 0.045, chi(2) test). As for concomitant FNB, our series displayed a high rate of diagnostic concordance (88.8%). Conclusions: Despite numerous data published, it is still unclear which is the most feasible method to use; therefore, we compared FNA, FNB, or their combination to understand the best applicable technique. Our experience confirmed that FNA is extremely efficient in the diagnosis of biliopancreatic lesions, especially in the hands of expert endoscopists and pathologists. Considering anatomic location, EUS-FNA is more accurate for mass-forming neoplasms in the pancreatic parenchyma rather than for lesions of the biliary system. Moreover, concomitant FNB usually confirmed the cytological diagnosis, allowing a deeper immunohistochemical characterization of the neoplasia. This proves that a "pure" cytology and "pure" histology approach should be looked differently since these are complementary techniques especially if we can obtain a cellblock from FNA.