FRI270 A Rare Case Of Giant Benign Pheochromocytoma

Disclosure: M.S. Hossain: None. B. Gautam: None. K. Mandal: None. H. Liao: None. D.S. Rosenthal: None. S.C. Kumar: None. Background: Pheochromocytomas are Catecholamine-secreting tumors that arise from the adrenal medulla. These tumors are rare however giant pheochromocytomas (>7 cm) are even rarer entities, which are thought to be more aggressive and malignant. Here we present a case of incidentally found giant but benign pheochromocytoma. Case Report: A 40-year-old female with no PMH presented to the hospital with fever & cough for 1 month which was associated with weight loss (10lb). Patient was started on antibiotics and CT revealed right-sided adrenal incidentaloma while searching for sources of infection. CT & MRI abdomen were done for better characterization, showed a round circumscribed right adrenal mass measuring 11.3 x 11.4 x 12.8 cm. Mass had irregular central necrosis, peripheral enhancement & neovascularization. Patient denied headache, sweating & palpitation; no personal or family history of pheochromocytoma. On physical examination BP: 103/70, HR: 98, Temp: 98F, BMI:25.9, unremarkable for cushingoid features, virilization & hirsutism. Hormonal workup showed elevated free normetanephrine 185 (<148pg/ml) & chromogranin A 801 (<311ng/ml), but normal free metanephrine <25 (<57pg/ml) & total metanephrines 185 (<205pg/ml). 24hr Urine study: elevated total metanephrines 1661 (182-739mcg/24h) & normetanephrine 1482 (88-649mcg/24h) but normal metanephrine 179(58-203mcg/24h), urine volume 2360ml/24h, urine creatinine 0.87(0.50-2.15g/24h). Patient Cortisol, ACTH, Aldosterone, Renin activity, DHEA-S, Androstenedione was normal. Patient was started on alpha-blockers. Patient underwent successful right-sided adrenalectomy & nephrectomy with IVC resection. Pathology reported pheochromocytoma stage II T2Nx, Ki 67 <5%. No vascular and extracapsular invasion & no mitosis. Post operative outpatient follow up showed elevated plasma free normetanephrine 199(<148pg/ml) & normal free metanephrine <25 (<57pg/ml) & total metanephrine 199 (<205pg/ml). 24hr urine study: normal metanephrine 61 (58-203mcg/24h), Normetanephrine 268 (88-649mcg/24h) & total metanephrines 329 (182-739mcg/24h). Patient was advised for Ga68 DOTATE/PET scan, genetic counseling & lifelong follow-up with endocrinology for surveillance. Discussion: Pheochromocytoma symptoms may vary regardless of tumor size. Giant pheochromocytoma may not have high secretory potential due to central necrosis resulting in reduced chromaffin cells or catecholamines that are restricted to capsular mass which may release into the bloodstream intraoperatively(1). Therefore, initiating alpha-blockers before surgery in these cases may prevent perioperative complications.1. Minei S, Yamashita H, Koh H, Satoh T, Kobayashi S, Furuhata M, et al. Giant cystic pheochromocytoma A case report. Hinyokika Kiyo. 2001;47:561-3. Presentation: Friday, June 16, 2023