ASYMPTOMATIC PHEOCHROMOCYTOMA PRESENTING AS ADRENAL INCIDENTALOMA

Abstract

INTRODUCTION
Adrenal incidentalomas remain a diagnostic dilemma for endocrinologists. Pheochromocytoma is the most critical of the differential diagnosis that needs to be ruled out because of its fatal consequences. More commonly symptomatic with elevations of blood pressure during spells of catecholamine secretion, a subset of patients has been reported with normal blood pressure. We present a clinically asymptomatic female that was evaluated for an incidental mass on her right adrenal.

CASE
A 32-year-old female consulted for a right adrenal mass noted on routine ultrasound for abdominal discomfort. She had no history of hypertension nor fluctuations of blood pressure up to initial evaluation. CT scan of abdomen with contrast showed a 3x4x3 cm right adrenal mass, with slow wash-out on delayed scan. She had elevated 24-hour urine metanephrine 1.96 mg/24 hrs (NV: 0-1), 24-hour urine epinephrine 129 mcg/24hrs (NV:2-24) and chromogranin A levels 225.38 ng/ml (NV:<100). 24- hour urine norepinephrine 84 mcg/24 hrs (NV 15-100) and dopamine 349 mcg/24 hrs (NV:52-480) were normal. Aldosterone-to-renin ratio was 56.21 (NV:<20 ng/dl per ng/ml/hr), with low renin 0.14 (NV:0.48-4.88 ng/ml/ hr) and normal aldosterone 7.87 (NV:5.38-38.76 ng/dl). Luteinizing hormone 4.33 (NV:3.5-12.5 mIU/ml), folliclestimulating hormone 3.21 (NV:<7 mIU/ml), estradiol 67.7 (NV:15-350 pg/ml). 8 am serum cortisol (28.28 nmol/L) was appropriately suppressed after overnight 1 mg dexamethasone. Alpha blocker and calcium channel blocker were given preoperatively. Laparoscopic adrenalectomy revealed a 4.5cm adrenal tumor. There were extreme fluctuations in blood pressure during tumor manipulation. Histopathology confirmed the pheochromocytoma.

CONCLUSION
Asymptomatic pheochromocytoma is a rare and potentially fatal finding in the background of adrenal incidentaloma. Proper diagnosis and perioperative management are essential for the successful removal of these tumors.