SUN-497 Epinephrine-Secreting Paraganglioma: A Rare Retroperitoneal Mass Case

Abstract Disclosure: A.M. Aviles Melendez: None. O. Onwudiwe: None. Z. Li: None. Catecholamine-secreting tumors are rare neoplasms seen in 0.1-0.6% of patients with hypertension. Although usually bening in nature, high mortality and morbidity is associated. Most are sporadic, but 40% are associated with genetic predisposition, especially paragangliomas. Paragangliomas comprise 15-20% of these cases, with most being “biochemically silent”, but some may secrete norepinephrine primarily. We present a case of a paraganglioma secreting mostly epinephrine, discovered in the setting of hypertensive crisis upon biopsy for evaluation of hypertension and headaches. A 56-year-old male with history of essential tremors and hyperlipidemia was evaluated for labile blood pressure and bilateral throbbing headache of fluctutating duration and intensity, worsening upon bending over, associated with palpitations and severe posterior neck pain. Denied other symptoms. Family history essential tremors in brother. On beta blocker therapy for tremors, recently stopped due to no pereceived benefits. Abdominal MRI with and without contrast showed a 5.4 x 4.4 x 5.2cm mild to moderate T2 hyperintense, T1 isointense lesion at the left paracaval retroperitoneal region, with minimal postcontrast enhancement. Whole-body PET scan showed a 5.4 x 4.4cm aortocaval lesion with mild Fluorodeoxyglucose uptake SUV max 5.0, concerning for neoplastic process, for which biopsy scheduled. Upon CT-guided biopsy initiation, patient developed severe hypertension of 246/119mmHg, and right-sided chest pain, which led to procedure termination and admission to the hospital. Biochemical workup for catecholamine-secreting tumor remarkable for markedly elevated levels of plasma metanephrine at 8.6 nmol/L (N: <0.50 nmol/L), plasma normetanephrine at 4.1 nmol/L (N:<0.9 nmol/L), 24-hour urine metanephrine at 8514 mcg/24hr (N: 44-261 mcg/24hr) and normetanephrine at 2150 mcg/24hr (N: 128-484 mcg/24hr). Normal cortisol, renin, and aldosterone levels. Started on doxazosin, then beta blocker, high fluid intake, and scheduled for exploratory laparotomy. A 7.8cm right retroperitoneal aortocaval tumor was resected, with excision of adjacent celiac and periportal lymph nodes. Biopsy remarkable for extra-adrenal paraganglioma with vascular and capsular invasion, and extension into adipose tissue, consistent with aggressive behavior. Patient referred for genetic testing. Paragangliomas secreting mostly epinephrine are seen in about 2 people per million, for which this is a very rare presentation, and they lead to hypertension, headache and palpitations, as in our patient. This case highlights the importance of biochemical testing prior to imaging, to avoid hypertensive crisis, the importance of surgical exploration despite imaging localization, as tumor found on right side instead of left as imaging showed, as well as the varied presentation of paragangliomas. Presentation: Sunday, July 13, 2025