Clinical Utility of EUS ‐ FNA / FNB for Diagnosis and Grade Assessment in Pancreatic Neuroendocrine Tumors < 20 mm: A Systematic Review and Meta‐Analysis

Objective Management of pancreatic neuroendocrine tumors (pNETs) < 20 mm remains controversial. Endoscopic ultrasound‐guided tissue acquisition is crucial for diagnosis and grading, but data on small pNETs and Ki‐67 sample adequacy are limited. This systematic review and meta‐analysis evaluated sample adequacy, diagnostic yield, and histologic concordance with surgical specimens. Methods A systematic search of MEDLINE, EMBASE, and SCOPUS was conducted. Studies reporting diagnostic yield or concordance between EUS‐guided fine‐needle aspiration (FNA) or biopsy (FNB) and surgical histology in pNETs < 20 mm were included. The primary outcomes were diagnostic yield, concordance with surgical histology, and adequacy of samples for Ki‐67‐based tumor grading. Pooled estimates were calculated using random‐effects models. Results 27 studies were included: 17 reported sample adequacy, 9 diagnostic yield, 13 grade concordance, and 5 both yield and grading. Pooled diagnostic yield was 84.4% (95% CI: 0.80–0.87) and pooled concordance rate was 84.2% (95% CI: 0.803–0.882). For sample adequacy to establish tumor grade, the pooled rate was 71.6%. Notably, EUS‐FNB demonstrated significantly higher adequacy (79.8%) compared to FNA (52.5%). Conclusion EUS‐guided tissue acquisition offers high diagnostic accuracy and reliable tumor grading in pNETs < 20 mm. FNB outperforms FNA in obtaining adequate tissue for grading, underscoring its importance in clinical decision‐making.