SUN-902 Bradycardia as a Presentation of Malignant Pheochromocytoma

Introduction Pheochromocytoma usually presents with tachycardia, hypertension and other symptoms related to catecholamine release. Bradycardia has been reported in up to 10% of patients and is due to an unusual reflex to cathecolamine surge. Case Report: 57-year-old morbidly obese female with a history of COPD, hypertension, paroxysmal bradycardia, and urinary incontinence was referred to endocrinology clinic after an adrenal mass was found incidentally as part of a work-up for microscopic hematuria and urinary incontinence. CT abdomen showed unilateral 3.3 x 3.9 cm left lobular adrenal mass. Family history was negative for malignancies or pheochomocytoma. Patient denied substance abuse or ethanol use. Her medications include amlodipine, hydrochlorothiazide and albuterol. Physical exam was remarkable for a BMI of 51.6 and bradycardia of 50 bpm and well controlled blood pressure. On further review of her history, patient had prior visits to outpatient and emergency department for chronic headaches, insomnia, palpitations and sweating. Patient had a previous admission 13 years prior for chest pain and hypertensive urgency associated with headache and junctional bradycardia. Laboratory workup was significant for serum metanephrine levels of 749 pg/ml (normal <42), serum normetanephrine 185 pg/ml(normal <145), serum chromogranin A 130 ng/L(normal <39) and 24hr urine metanephrine of 1340 ug/24hr (normal <96) and urine normetanephrine of 357 ug/24hr (normal <80). Previous ECG showed sinus bradycardia. Echo-cardiogram revealed normal ejection fraction with left atrial enlargement. MIBG showed large focal area of intense radio-tracer accumulation in left mid abdomen and small focal lesions in the liver. Diagnosis of malignant pheochromocytoma was made and patient was referred to another institution for further management. Conclusion: Malignant pheochromocytoma is a rare neuroendocrine tumor that usually presents with tachycardia and hypertension. 10% of patients with malignant pheochromocytoma can debut with bradycardia due to sinus arrest. Although malignant and benign pheochromocytoma share the same clinical and histological features, the presence of metastasis is the main clue to differentiate them. Surgery remains the main treatment option even if complete debulking cannot be achieved. Nuclear radiation therapy or chemotherapy are two other therapeutic options that can be considered alone or in combination with surgery depending on the patients’ comorbidities. Lifetime surveillance is recommended as recurrence can occur up to 40 years after original resection. References-Chen H, Sippel RS, O’Dorisio MS, Vinik AI, Lloyd RV, Pacak K. The North American Neuroendocrine Tumor Society consensus guideline for the diagnosis and management of neuroendocrine tumors: pheochromocytoma, paraganglioma, and medullary thyroid cancer. Pancreas. 2010 Aug;39(6):775-83.