S3234 A Tumor in the Pipeline: Pancreatic Neuroendocrine Tumor Presenting With Pancreatic Ductal Obstruction and Hyperglycemia

Introduction: Pancreatic neuroendocrine tumors (PanNETs) are rare neoplasms that arise from the neuroendocrine cells of the pancreatic islets and are classified as either functioning or nonfunctioning. Most PanNETs are sporadic, however approximately 10% occur in the context of hereditary syndromes. Functioning PanNETs often present associated with characteristic hormone-related syndromes, while nonfunctioning tumors typically present due to mass effect or are found incidentally. Diagnosis relies on a combination of biochemical markers, imaging, and endoscopic ultrasound (EUS). Here, we present a case of a nonfunctioning PanNET found incidentally as the cause of abdominal pain and main pancreatic duct obstruction with associated hyperglycemia. Case Description/Methods: A 51-year-old woman with a history of hypertension presented for evaluation of right upper quadrant and epigastric abdominal pain with radiation to the back as well as nausea and vomiting. Initial labs including liver function tests and lipase were negative. Her fasting glucose levels were around 140-150 mg/dL. A computed tomography abdomen and pelvis and magnetic resonance cholangiopancreatography showed asymmetric atrophy of the pancreatic body and tail with central main pancreatic ductal dilation with a 9 mm enhancing nodule producing a focal cutoff sign. The patient underwent an upper EUS which showed a 13 × 7 mm hypoechoic and heterogeneous mass in the pancreatic body with poorly defined borders causing upstream main pancreatic ductal dilation measuring 6.7 mm. Fine needle biopsy was performed with pathology showing a low-grade, well-differentiated neuroendocrine tumor, suggesting that the PanNET, while nonfunctioning, was impairing the function of the pancreas, resulting in hyperglycemia. Discussion: PanNETs are rare neoplasms representing a heterogeneous group of tumors, are classified as either functioning or nonfunctioning, and are distinct from the more common pancreatic ductal adenocarcinoma. Functioning PanNETs are typically found in association with a presenting syndrome while nonfunctioning PanNETs are typically found incidentally or due to mass effect. However, this case highlights that a nonfunctioning PanNET may also impact the function of the pancreas, as the size was likely impacting function. If this patient had presented later on, it is possible that they would have presented with sequalae of hyperglycemia secondary to a non-functioning pancreas including dehydration and potentially diabetic ketoacidosis.