8275 Recurrent Retroperitoneal Paraganglioma

Abstract Disclosure: J. Kang: None. V. Gupta: None. J.S. Subauste: None. Paragangliomas are rare, highly vascular neuroendocrine neoplasms that may originate from sympathetic or parasympathetic paraganglia and may secrete catecholamines. They are closely related to pheochromocytomas which are considered to be their intra-adrenal counterparts. A 65-year-old African American male with type 2 diabetes and tobacco use presented to his primary care physician with night sweats and unintentional weight loss of about 30 pounds in 3 months. Review of systems and laboratory workup was unremarkable. CT Chest/Abdomen/Pelvis with contrast showed a homogenous, well-circumscribed 4.6cm retroperitoneal mass causing mass effect on portal vein, Inferior vena cava, and right renal artery. Interventional radiology performed fine needle aspiration with intra-procedural blood pressure rising to 201/70 mmHg. Pathology showed paraganglioma, staining positive for synaptophysin, chromogranin A, CD 56 and S-100 protein. Plasma metanephrines were elevated at 2818 pg/mL, plasma normetanephrines at 1247 pg/mL with consistent 24-hour urine results. Workup for other adrenal hormones was negative. No family history of pheochromocytoma/paraganglioma or any clinical manifestations of Von-Hippel-Lindau syndrome or Neurofibromatosis were present. He was started on alpha blockade followed by beta blocker and surgical resection was planned. In the interim, escalating requirements of insulin were noted. Intra-operative course was complicated by systolic blood pressure rising to 290s which resolved after mass was removed. Immunohistochemical studies sent to Mayo, Rochester showed retained cytoplasmic SDHB expression in tumor cells. Hence, no further genetic testing was performed. Post excision, plasma-free metanephrines normalized with significant improvement in blood pressure and diabetes. He was followed with yearly plasma-free metanephrines for surveillance. Although asymptomatic, a three-fold rise of plasma metanephrines was noted five years later. CT Abdomen was concerning for recurrence. Dotate/PET scan showed dotate-avid para-aortic soft tissue lesion measuring 2.3 cm between the celiac artery and the superior mesenteric artery which was surgically excised with pathology consistent with paraganglioma (Ki67<1%). Diagnosis of paragangliomas is often in 3rd - 5th decade. About 30% are hereditary and associated with Von-Hippel-Lindau, Neurofibromatosis-1, MEN2A/B among other syndromes. They are mostly benign but SDHB pathogenic variants are likely to be malignant. Genetic testing should be considered in all paraganglioma patients to screen for germline pathogenic variants in SDH and other genes. Diagnosis of secretory paraganglioma is by urinary and/or plasma fractionated metanephrines and catecholamines. Treatment of choice is surgery when amenable to resection with preoperative medical blockade to prevent perioperative complications. Presentation: 6/1/2024