Unusual, Metastatic, or Neuroendocrine Tumor of the Pancreas: A Diagnosis with Endoscopic Ultrasound–guided Fine-needle Aspiration and Immunohistochemistry

Background/Aim: To determine the yield of endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) in combination with immunostains in diagnosing unusual solid pancreatic masses (USPM) in comparison with pancreatic adenocarcinoma (ACP). Patients and Methods: All EUS-FNA of solid pancreatic masses performed with a 22-gauge needle were included. Data on clinical presentations, mass characteristics, presence of pancreatitis, yield of tissue, and final diagnosis were compared between the two groups. On site cytopathology was provided and additional passes were requested to perform immunostains. Results : Two hundred and twenty-nine cases with either adenocarcinoma or USPM were included. The median age of the cohort was 65 years. ACP (210/229, 92%) accounted for the majority of the cases. The USPM included neuroendocrine (NET) masses (n=13), metastatic renal carcinoma (n=3), metastatic melanoma (n=1), lymphoma (n=1), and malignant fibrous histiocytoma (n=1). Subjects with ACP were significantly more likely to present with loss of weight (P=0.02) or obstructive jaundice (P