S3521 The Hidden Tumor: Pancreatic Cancer Missed by Imaging, Found by Endoscopic Ultrasound

Introduction: Pancreatic cancer continues to carry a high morbidity and mortality due to poor early detection rates. Subtle changes or ductal changes in the pancreatic or biliary ducts can be early signs of malignancy even in the absence of an observed mass on imaging modalities. This report presents 3 patients with pancreatic cancer found in endoscopic ultrasound (EUS) without corroborative findings on cross-sectional imaging before EUS. Case Description/Methods: Case 1: A 78-year-old woman presented with acute-on-chronic pancreatitis. Previously, she had 4 endoscopic retrograde cholangiopancreatographies (ERCPs)s to evaluate choledocholithiasis, with the most recent exam showing pneumobilia, moderate biliary and pancreatic duct (PD) dilation without evidence of a stone. Magnetic resonance imaging/magnetic resonance cholangiopancreatography (MRCP) on admission showed pneumobilia and PD dilation up to 1 cm with pancreatitis and no evidence of a mass. EUS of the pancreatic head revealed a hypoechoic irregular mass with upstream PD dilation, and FNB confirmed pancreatic ductal adenocarcinoma (PDAC). A PD stent was placed for pancreatic pain symptoms during her endoscopic retrograde cholangiopancreatography (ERCP). Case 2: An 86-year-old woman with a history of Sjögren’s syndrome presented with complaints of ongoing loose stools. Notable lab findings included a low fecal elastase (less than 5.7 mmol/L) and elevated Ca19-9 (893). Computed tomography abdomen and subsequent MRCP performed for her diarrhea showed pancreatic atrophy with a dilated PD up to 1.1 cm. No discrete mass was seen, and the biliary tree was normal. EUS examination of the pancreatic head revealed an irregular mass, along with upstream PD dilation. Case 3: A 54-year-old man, with presumed stage IV colon cancer (diagnosis was presumed by Carcinoembryonic Antigen, although no mass was seen in colonoscopy), presented with obstructive jaundice and liver metastases. He was treated with FOLFOX-6/Avastin for 1 year without resolution. EUS examination, as part of his workup for jaundice, confirmed the presence of a pancreatic neuroendocrine tumor. Discussion: These cases demonstrate the importance of utilizing endoscopic ultrasound in detecting pancreatic neoplasms in the setting of changes in the pancreatic or biliary ducts with incidental radiographic findings. A high level of suspicion is needed when such changes are observed on imaging to assess malignancy, and this would typically be evaluated and biopsied using endoscopic ultrasound. Given that a considerable number of patients may derive benefit from early diagnosis, further research is warranted to determine optimal screening protocols using EUS.