S3551 Presentation of Rare Pancreatic Oncocytic Intraductal Papillary Mucinous Neoplasm in a 73-Year-Old Woman

Introduction: Pancreatic oncocytic intraductal papillary mucinous neoplasm (IOPN) is a very rare subtype of intraductal papillary mucinous neoplasm (IPMN), representing about 5% of all intraductal pancreatic neoplasms. Clinically, it often poses diagnostic challenges due to non-specific abdominal symptoms. They usually present as large cystic lesions in the head of the pancreas that are discovered incidentally. Case Description/Methods: We present the case of a 73-year-old woman with past medical history of adenomatous colon polyps and lung nodules who underwent a computed tomography chest with contrast for routing monitoring of lung nodules. The imaging showed some concerning lesions in her pancreas which prompted a referral to gastroenterology. Computed tomography abdomen with contrast showed a hyper enhancing mass in the tail of the pancreas. The patient denied any obvious symptoms such as abdominal pain, diarrhea, weight loss or jaundice. CEA, CA19-9 and HBA1C levels were checked and were within normal range. She then underwent magnetic resonance imaging of the abdomen with contrast which confirmed a complex, mixed solid and cystic mass in the pancreatic tail measuring 25 mm × 24 mm. The mass was also communicating with the main pancreatic duct. Atrophy of the pancreas and dilation of the main pancreatic duct distal to this mass was also noted. Radiological evaluation was nonspecific but favored the mass as a cystic degeneration of a neuroendocrine tumor. The patient was then referred to General Surgery and underwent distal pancreatectomy and splenectomy. Pathology results from the surgical specimen showed IOPN involving the main pancreatic duct, 12 benign lymph nodes and a normal spleen. There was no evidence of invasion. She did well post operatively and received appropriate post-splenectomy vaccines as well, eventually being discharged on post op day 5. At her 6 month follow up, she is asymptomatic without imaging evidence of recurrence on magnetic resonance imaging abdomen. Discussion: Pancreatic IOPN is a pancreatic tumor that is more frequently discovered in males around the seventh decade of life. The recommended treatment is surgical resection due to the risk of invasive carcinoma, which is present in nearly 50% of IOPN cases. Our patient did not have invasive neoplasm but underwent distal pancreatectomy and splenectomy to ensure complete resection, especially due to the close proximity to the splenic vessels. Post operative outcomes for IOPN are generally favorable, with low rates of recurrence when complete resection is achieved.