S3237 Pancreatic Paraganglioma: A Rare Tumor With Diagnostic Challenges

Introduction: Pancreatic paraganglioma is a rare tumor and is usually benign. Here we present a case of pancreatic paraganglioma that was initially diagnosed with pancreatic neuroendocrine tumor. Case Description/Methods: A 70-year-old man presented to the hospital with acute ascending cholangitis due to choledocholithiasis. A contrast-enhanced computed tomography of the abdomen incidentally revealed a 4.4 cm solid hypodense mass at the tail of the pancreas. Endoscopic ultrasonography demonstrated a 47 mm × 40 mm hypoechoic, focally anechoic, solid, cystic, heterogeneous, irregular mass at the tail of the pancreas. A fine needle biopsy of the mass was performed. Histopathology showed a well-differentiated neuroendocrine tumor. The patient underwent a distal pancreatectomy and splenectomy. Histopathology of the pancreatic mass with hematoxylin and eosin stain revealed epithelioid cells arranged in a trabecular pattern separated by a vascular network (zellballen pattern). The immunohistochemical staining showed strong nuclear reactivity for GATA3 and loss of expression of SDHB, supporting the diagnosis of pancreatic paraganglioma. There was no lymphovascular invasion. At 6-month follow-up, the patient remained symptom-free without evidence of distant metastasis on a contrast-enhanced computed tomography of the chest, abdomen, and pelvis. Discussion: The paraganglia are clusters of neuroendocrine cells consisting of both sympathetic and parasympathetic nervous systems. Pancreatic paragangliomas are extremely rare. They are usually benign and non-functional. In functional tumors, symptoms may mimic pheochromocytoma due to high levels of catecholamine. The disease is often indistinguishable from pancreatic neuroendocrine tumor preoperatively. In this case, despite extensive imaging and biopsy, the diagnosis was confirmed postoperatively. This case highlights the limitations of current diagnostic modalities and the importance of using the immunohistochemical stain in distinguishing between pancreatic neuroendocrine tumors and paragangliomas. Surgical removal of the tumor is the definitive treatment for pancreatic paraganglioma. Additionally, the preoperative diagnosis of paragangliomas is crucial for surgical planning due to the need for alpha-blockade medications to prevent intraoperative hemodynamic instability. Recognition of this rare neoplasm is also important for appropriate genetic counseling and postoperative management.