A Case of Normotensive Pheochromocytoma with Extreme Elevation of Normetanephrines

Presentation Number: SAT 396
Date of Presentation: April 1st, 2017

Mohamad Rachid*, Samantha Tan, Irfan Siddiqui and Tahira Yasmeen
Advocate Christ Medical Center, Oak Lawn, IL

Abstract

Background:

Pheochromocytoma (PC) is a neuroendocrine catecholamine secreting tumor that originates from the adrenal medulla. We present a case of pheochromocytoma presenting initially with abdominal pain with extreme elevation of plasma normetanephrines. This case highlights the challenges in preoperative management of a patient with pheochromocytoma and associated with low normal blood pressure.

Case:

A 40 year old female with no medical history presented with complaints of vague right-sided abdominal pain of 2 weeks associated with hot flashes. Physical exam showed blood pressure of 115/85 mmHg and heart rate of 75 beats per minute. A Computed Tomography (CT) of abdomen without contrast showed a 6 cm soft tissue attenuation on the right adrenal. A follow up CT abdomen with contrast confirmed a 6 cm right adrenal mass with marked hypervascularity and no significant washout consistant with PC. A MIBG scan showed large solitary right adrenal lesion consistent with PC with no other abnormal MIBG activity seen. Lab evaluation revealed elevated plasma metanephrine of 0.78 nmol/L (0.00-0.49 nmol/L), plasma normetanephrine >50 nmol/L (0.00-0.89 nmol/L), urine metanephrine of 449 mcg/24hr (52-341 mcg/24h), urine normetanephrine 18233 mcg/24hr (88-444 mcg/24h), and urine epinephrine of 9 mcg/24hr (2-24 mcg/24hr). Blood pressure remained normal to low with a systolic blood pressure of 110-80 mmHg and diastolic blood pressure of 80-55 mmHg. Surgical resection of PC was contemplated with preoperative preparation with alpha blockade. As alpha blockers could further worsen the hypotension, the patient was observed in the hospital for 24-hours and therapy initiated with phenoxybenzamine 10 mg twice daily. Liberal fluid and dietary salt intake was encouraged. She was given sodium chloride tablets 1 gm three times daily. After one week of phenoxybenzamine, beta blockade was initiated with metoprolol 12.5 mg daily for tachycardia. The patient underwent laparoscopic right adrenalectomy without complications. Phenoxybenzamine and metoprolol were stopped after surgery and the patient was discharged 2 days later in stable condition. After 6 weeks, repeated work up showed low plasma metanephrine < 0.10 nmol/L (0.00-0.49 nmol/L) and plasma normetanephrine 0.30 nmol/L (0.00-0.89 nmol/L).

Conclusion:

We present a rare case of normotensive pheochromocytoma with extreme elevation of plasma normetanephrines and normal metanephrines which was managed successfully with pre-operative alpha blockade using phenoxybenzamine and beta blockers. This case highlights the challenges in the preoperative management of normotensive PC and demonstrates successful management with alpha and beta blockers without complications. In addition this case reinforces the need for prospective clinical trials to address the optimum management of normotensive pheochromocytoma.

 

Nothing to Disclose: MR, ST, IS, TY