Endoscopic Ultrasound Assessment of Pancreatic Duct Diameter Predicts Neuroendocrine Tumors and Other Pancreas Masses.

Objectives Distinguishing neuroendocrine tumors (NETs) and other pancreas lesions from adenocarcinomas via endoscopic ultrasound (EUS) requires additional tissue for special staining and processing. Our aim was to determine if main pancreatic duct (PD) diameter on EUS helps to differentiate NET and other unusual tumors from adenocarcinoma. Methods We evaluated 30 consecutive patients diagnosed with NET or other pancreas lesions by EUS with 90 matched patients who were found to have adenocarcinoma. Dilated PD was defined as greater than 3 mm. Multivariate logistic regression was used to evaluate associations between lesion type and PD diameter. Results Among the 30 patients with NET/other pancreas lesions, 21 had NETs, 7 had metastases, and 2 had lymphomas. A dilated PD was demonstrated in only 3.3% of pancreatic NET/other lesions but present in 88.9% of cases of primary adenocarcinoma (P < 0.01). In multivariate analysis, a normal PD diameter and absence of clinical symptoms strongly predicted the presence of pancreatic NET/other versus adenocarcinoma (P < 0.01). Conclusions The absence of PD dilation upstream of the lesion suggests NET or other lesions rather than adenocarcinoma. This finding should prompt endosonographers to obtain additional tissue at the time of EUS to send for special studies.