Giant Non-Functioning Neuroendocrine Tumor of the Pancreatic Body Mimicking a Lesser Omentum Mass and Invading the Liver and Stomach: A Case Report

Introduction: Pancreatic neuroendocrine tumors are rare neoplasms, most of which are non-functioning. Because they cause no hormonal syndrome, they are often diagnosed late, when they have reached a large size. Their location and their relationships with adjacent organs may make the preoperative identification of the organ of origin difficult. Case presentation: We report the case of a 60-year-old woman with treated asthma who presented with a one-year history of progressively worsening epigastric pain radiating to the back. Physical examination and laboratory tests were normal, including gastrinemia, blood glucose, the other secretory neuroendocrine markers and urinary metanephrines. Abdominopelvic computed tomography showed a 9 cm hypervascular mass in the lesser omentum, in contact with the pancreas, liver and stomach, supplied by a branch of the celiac trunk. Endoscopic ultrasound-guided biopsy concluded to a low-grade neuroendocrine tumor. Surgery was indicated because of the tumor size and symptoms. Exploration revealed a highly vascularized neuroendocrine tumor arising from the pancreatic body and invading the left lobe of the liver and part of the stomach. A distal (body and tail) pancreatectomy was performed after meticulous dissection, and histopathology of the specimen confirmed a neuroendocrine tumor. The postoperative course was uneventful and the patient was discharged on postoperative day 5. Conclusion: A giant non-functioning pancreatic neuroendocrine tumor may mimic a lesser omentum mass. Surgical resection, even with locoregional invasion, remains the treatment of choice when feasible.