Role of Endoscopic Ultrasound and Endoscopic Ultrasound-Guided Fine-Needle Aspiration in Diagnosing Metastasis to the Pancreas: A Tertiary Center Experience

Background: Metastasis to the pancreas (MP) is a rare entity that is difficult to identify by imaging alone. Few reports have described endoscopic ultrasound (EUS) and EUS-guided fine-needle aspiration (FNA) findings. Herein, we try to describe the EUS and EUS-FNA characteristics of MP. Methods: This retrospective study compared 28 patients with MP (13 males; mean age: 60.1 8 12.6 years) and 60 control patients (30 males; 62.7 8 11.5 years) with pancreatic ductal adenocarcinoma (PDAC). All lesions were characterized by EUS, and MP was diagnosed by EUS-FNA (n = 16), surgery (n = 6) or both (n = 6). Results: Multivariate logistic regression revealed that the presence of regular borders (p = 0.004; OR: 8.81, 95% CI: 1.97-39.4), the absence of retention cysts (p = 0.045; OR: 12.5, 95% CI: 1.06-147.0), and the absence of main pancreatic duct (MPD) dilation (p = 0.003; OR: 8.18, 95% CI: 2.04-32.8) were predictors of MP rather than PDAC. The EUS-FNA sampling adequacy was 95.4% (21/22), and the cor- rect diagnosis was obtained in 95.2% (20/21) of cases when K-ras mutation analysis and/or immunostaining were added. Conclusion: The presence of regular borders, the absence of retention cysts and the presence of nondilated MPD on EUS indicate MP rather than PDAC. This diagnosis can be accurately confirmed by EUS-FNA with immunostaining and/or K-ras analysis.