Frequency of mediastinal lymph node metastases in patients undergoing EUS evaluation of pancreaticobiliary masses

Background. Mediastinal lymph node metastases; have rarely been reported in patients with pancreatic cancer. Our aim was to determine the frequency of mediastinal lymph node metastases in patients with pancreaticobiliary masses by using EUS-guided fine needle aspiration. Methods: Sixty-six consecutive patients with pancreatobiliary masses were evaluated on EUS for the presence of mediastinal lymph node metastases. All masses were staged by commonly used EUS criteria by using sector scanning echoendoscopes. Mediastinal lymph nodes with EUS features that suggested malignancy were aspirated. Results. Of the 66 patients (mean age 65.6 years; 38 men), 4 had biliary masses, 5 had lesions of the major duodenal papilla, and 57 had pancreatic masses. Eleven patients (10 pancreatic masses, 1 biliary mass) had enlarged mediastinal lymph node (12-30 mm) on EUS; in 2 patients these had a benign appearance and were not aspirated. Nine patients underwent EUS-guided fine needle aspiration: in 1 the cytology was inconclusive (patient subsequently had a negative Whipple resection); in 4 the mediastinal lymph node cytology was benign; the remaining 4 patients had adenocarcinoma cells in the aspirate from mediastinal lymph node. These 4 pancreatic tumors were staged by EUS as T2N1M1 (1), as T4N0M1 (2, one later found to also have a lung mass), and T4N1M1 (1). Conclusion: Enlarged mediastinal lymph nodes were found on EUS in 16.6% (95% Cl [7.7%, 25.6%]) of patients with pancreatobiliary masses and in 17.5% (95% Cl [7.6%, 27.4%]) of patients with pancreatic masses. The frequency of mediastinal lymph node metastases in pancreatobiliary masses was 6.1% (95% CI [0.34%,11.9%]) and in pancreatic masses 7.0% (95% CI [0.4%,13.6%]). Routine EUS evaluation of the mediastinum in patients with pancreatic masses is warranted.