SAT-491 Bilateral Pheochromocytomas in Neurofibromatosis Type 1

Abstract Disclosure: K. Mitrollari: None. C. Chukwunenye: None. M.S. Kazi: None. M. Paravastu: None. M.H. Kazi: None. Background: Pheochromocytoma is a rare manifestation in patients with Neurofibromatosis Type 1 (NF1). The incidence of bilateral pheochromocytomas is even rarer (0.01-0.5%.) We present a case of an NF1 patient with uncontrolled hypertension and abdominal pain who was diagnosed with bilateral pheochromocytomas. Clinical Case: A 48 y/o male with history of NF1 mutation (p.W571Gfs*15) and hypertension presented with generalized abdominal pain and increased urinary frequency. Additionally, his blood pressure remained elevated despite five anti-hypertensive medications. A CT of the abdomen and pelvis showed a 7.1 cm left adrenal mass that was 46 HU and a 1.8 cm right adrenal nodule of 26 HU. Labs revealed plasma metanephrine 2.12 nmol/L [0.00-0.49], plasma normetanephrine 7.05 nmol/L [0.00-0.89], 24-hr urine norepinephrine 442 µg/d [14-120], and 24-hr urine metanephrine 1,082 µg/d [55-320]. DHEA-S, renin, aldosterone, and aldosterone:renin ratio (1.0) were normal. PET dotatate scan revealed bilateral hypermetabolic adrenal masses. The patient was prescribed prazosin and underwent left adrenalectomy with improvement of hypertension. Surgical pathology confirmed pheochromocytoma. To preserve adrenal function, the patient was observed without right adrenalectomy. His catecholamines normalized over the next several months. At a 6-month follow up, his plasma normetanephrine was trending upwards at 0.95 [0.00-0.89 nmol/L] and 24-hour urine metanephrine was 384 ug/d [55-320 ug/d]. Repeat PET dotatate scan revealed an increase in the hypermetabolic activity of the right adrenal nodule. He was started on doxazosin prior to total right adrenalectomy. Surgical pathology confirmed pheochromocytoma. Post-operatively, the patient was started on physiologic dose of hydrocortisone and fludrocortisone. At his 1-year follow-up, there was no recurrence, and the patient no longer required antihypertensive medication. Discussion: Pheochromocytomas are an uncommon manifestation of NF1, and bilateral involvement is rare. Ideally, in patients with small pheochromocytomas and a genetic syndrome or bilateral pheochromocytomas, cortical-sparing adrenalectomy is the preferred approach. It involves removing only the tumor while preserving some adrenal function, though this procedure may not be available at all medical centers. It also may not preserve enough adrenal cortex to avoid lifelong steroid replacement. This case underscores the importance of considering pheochromocytomas even in patients who present with atypical signs without Menard's triad, or those who are diagnosed with genetic conditions that are not typically associated with pheochromocytomas. Timely and appropriate testing, along with prompt diagnosis and management is crucial to preventing life-threatening hypertensive crises. Presentation: Saturday, July 12, 2025