Endoscopic Ultrasound Through-The-Needle Biopsy of Pancreatic Cysts: Toward Procedure Standardization

EUS-guided through-the-needle microforceps biopsy (EUS-TTNB) was introduced as a new diagnostic tool to establish pancreatic cyst histotype and help to better risk stratify the patients. The aim of this study was to describe the technical success, diagnostic yield, and adverse events of through-the-needle biopsy and discuss the technique variations, focusing on future procedure standardization.

We performed a prospective single-center study including patients with presumed mucinous cysts harboring worrisome features or indeterminate cyst type on imaging, submitted to EUS-TTNB using Moray® microforceps between March 2018 and September 2021. Specimens were processed as a cell-block.

We included 40 patients. Technical success was 97.5%. The diagnostic yield was 72.5% for TTNB whereas for cyst fluid cytology/analysis it was 27.5%. Moreover, without TTNB 5 mucinous lesions would not have been diagnosed. TTNB had a sensitivity of 76% and a specificity of 91%, while FNA cytology had a sensitivity and specificity of 35% and 91%, respectively. Moreover for IPMN lesions, subtyping was possible in 63% of cases. TTNB resulted in change in clinical management in 20% of patients. We registered three adverse events: 2 self-limited intracystic bleeding and 1 patient with abdominal pain not associated with pancreatitis.

TTNB proved superior to cyst fluid analysis and cytology for the definition of cyst histotype and mucinous cyst diagnosis with acceptable risk profile. Further studies should explore the best steps for procedure standardization.