The effect of solid pancreatic mass lesions on pancreatic duct diameter at endoscopic ultrasound

To evaluate the effect of solid pancreatic masses on the pancreatic duct (PD) at the endoscopic ultrasound (EUS) and the relationship of the location/size of a mass and PD dilation.

Patients who underwent EUS for pancreatic indications from 2011 to 2013 at a single center were retrospectively identified. Those with biopsies that revealed adenocarcinoma or neuroendocrine tumors in the pancreas were identified and PD size was ascertained from EUS, computed tomography, or magnetic resonance imaging.

Of the 475 patients who had a pancreatic EUS, 239 had a dilated PD and 236 had a normal PD. Patients with a dilated PD had a significantly higher incidence of pancreatic malignancy than those with a normal PD diameter (106/239, 44.4% vs. 32/236, 13.6%, P< 0.001). Of the 138 patients with a pancreatic malignancy, 106 (76.8%) had a dilated PD at some location in the pancreas. Over 80% of patients with a mass within the head, neck, or body had a dilated PD. For a mass located at the uncinate process or the tail, PD dilation was 65% and 23%, respectively. Fifty-six (80.0%) of the masses in the head, 11 (78.6%) masses in the neck, and 16 (76.2%) masses in the body had a dilated PD upstream of the mass. In addition, a step-wise increase in the incidence of PD dilation was correlated with an increase in mass size. About 67.6% of patients with masses measuring in the 1st quartile had dilated a PD, while 77.8%, 91.0%, and 71.4% of those with masses measuring in the 2nd, 3rd, and 4th quartiles, respectively, had a dilated PD.

PD dilation is a warning sign for pancreatic malignancies, however, small masses or masses at the uncinate process or the tail of the pancreas may not affect the size of the PD.