EUS-guided FNA of pancreatic metastases: a multicenter experience

Background: Metastatic lesions of the pancreas are a rare but important cause of focal pancreatic lesions. The purpose of this study is to describe the EUS features, cytologic diagnoses, and clinical impact of a cohort of patients with pancreatic metastases diagnosed by EUS-guided FNA (EUS-FNA). Methods: Over a 6-year period, in a retrospective, multicenter study, patients had the diagnosis of pancreatic metastases confirmed with EUS-FNA. All examinations were performed by one of 5 experienced endosonographers. The EUS and the clinical findings of pancreatic metastases were compared with those of a cohort with primary pancreatic malignancy. Results: Thirty-seven patients with possible metastases were identified, and 13 were excluded because of diagnostic uncertainty. The remaining 24 underwent EUS-FNA (mean passes 4.1) of a pancreatic mass without complications. Diagnoses included metastases from primary kidney (10), skin (6), lung (4), colon (2), liver (1), and stomach (1) cancer. In 4 (17%), 16 (67%), and 24 (100%) patients, EUS-FNA provided the initial diagnosis of malignancy, tumor recurrence, and pancreatic metastases, respectively. Four (17%) metastases initially were discovered by EUS after negative (n = 3) or inconclusive (n = 1) CT scans. Compared with primary cancer, pancreatic metastases were more likely to have well-defined margins (46% vs. 4%) compared with irregular (94% vs. 54%; p < 0.0001) margins. No statistically significant difference between the two populations was noted for tumor size, echogenicity, consistency, location, lesion number, or number of FNA passes performed. Conclusions: Pancreatic metastases are an important cause of focal pancreatic lesions and may occasionally be discovered during EUS examination after previously negative or inconclusive CT Use of immunocytochemistry, when available, may help to confirm a suspected diagnosis. These lesions are more likely to have well-defined EUS margins compared with primary pancreatic cancer.