A Real-world Comparison of FNB and FNA in IHC-required Lesions.

Current guidelines recommend FNA and FNB needles equally for pancreatic and other deep-seated lesions. However, some studies indicate that the sample adequacy for histologic evaluation is higher when using FNB compared with FNA needles. The diagnosis of neuroendocrine tumor (NET), autoimmune pancreatitis (AIP), and other gastrointestinal stromal tumors require high-quality tissue sampling for IHC diagnosis. Whether FNB is superior to FNA in these IHC-required lesions remains unclear. The investigators performed this at 2 tertiary care centers in China. The study prospectively collected patients undergoing EUS for a solid mass (\>1 cm) in the pancreas, abdomen, mediastinum, or pelvic cavity from December 2014 diagnosed with AIP, NET, mesenchymal tumors, and Lymphoma. Patients accepted FNB or FNA according to doctors' and patients' willingness in a real-world setting. All procedures were performed by experienced endosonographers; cytologists and pathologists were blinded to the sample collection method. Patients were followed for at least 48 weeks, and final diagnoses were obtained after surgery, imaging analysis, or resolution of the lesion. The primary aim was to compare diagnostic yields of EUS-FNA with EUS-FNB for all solid masses, then separately as AIP, NET, mesenchymal tumors, and lymphoma. The secondary endpoint was the quality of the histologic specimen.