EUS features of annular pancreas (with video) {A figure is presented}

Background: An annular pancreas is a rare congenital anomaly that results in a band of pancreatic tissue, either partially or completely encircling the duodenum. Objectives: In patients referred for an upper-GI (UGI) EUS (1) to determine the prevalence of an annular pancreas identified by EUS versus CT and (2) to describe the EUS features of an annular pancreas. Design: After review of UGI EUS procedures from January 1, 2000, through June 1, 2006, we conducted a retrospective review of EUS annular pancreas images to identify characteristic EUS features. Patients: This is the largest report describing the EUS findings in 5 patients. Results: Of 9776 patients undergoing UGI EUS, 5 patients (0.05%) (2 men; median age, 64 years; range, 44-69 years) were found to have an annular pancreas. EUS detected a band of pancreatic tissue that encircled the duodenum by 360° (n = 3), 270° (n = 1), or 180° (n = 1). Within this band of tissue, the pancreatic duct was identified in 4 of 5 patients. The ductal and parenchymal features within the annular band were identical to those within the remaining pancreas in all patients. None of the patients had hypoechoic ventral anlage. Limitations: Whereas, firm EUS criteria of an annular pancreas cannot be established based on 5 patients, certain features may prove useful for diagnosis. Conclusions: Although a diagnosis of an annular pancreas is rare, it should be considered in situations when a patient with possible associated symptoms has a normal CT.