Incidental Pheochromocytoma: Silent but Violent

Abstract Background: Pheochromocytoma is a rare catecholamine secreting neuroendocrine tumor. It arises from the chromaffin cells of adrenal medulla. It is diagnosed in 5–6.5% of adrenal incidentalomas which is not common. The usual clinical presentation includes the classic triad of sweating, headache and tachycardia. However, asymptomatic cases are seen in 8% of the patients with pheochromocytoma. We present a clinically asymptomatic patient diagnosed during work up of adrenal incidentaloma. The possible etiology for silent presentation includes one of the following:(i) Presence of a smaller functional tissue (ii)Accelerated turnover of the tumor causing release of the unmetabolized catecholamines in small amounts (iii) Pulsatile tumor secretion (iv)Tumors triggered by stress (v) Laboratory errors due to inappropriate handling of specimen at high-temperature (vi) False negative test results secondary to caffeine ingestion in the prior 24 hours. Clinical Case: 59 years old Caucasian female with past medical history of type 2 diabetes mellitus, obesity, essential hypertension, nonischemic cardiomyopathy, and asthma presented to the emergency room with complaints of worsening shortness of breath and pedal edema for 1 month. Physical exam: Blood pressure 146/78 mm of Hg and heart rate 82 beats/min, mild pedal edema, no pulmonary crackles. On imaging, CT angio chest showed irregularly enhancing right adrenal mass measuring 3.4 cm. This adrenal incidentaloma was not visualized on imaging done 5 years ago. Further, MRI abdomen revealed 4.1 cm right adrenal mass. Laboratory testing showed high total plasma metanephrines: 890 pg/ml (< or = 205), 24-hour urine metanephrines: 2337 (140–785), A1C: 10%. This confirmed the diagnosis of adrenal pheochromocytoma. Preoperatively, she was started on phenoxybenzamine 10 mg BID and encouraged on liberal salt intake. During the course, her blood pressure and heart rate were monitored daily. She underwent right adrenalectomy. Surgical pathology revealed 4.1 cm pheochromocytoma, negative margins with extension to the adipose tissues and vascular invasion, PASS score = 4. Post operatively, patient declined to get labs done. Due to high risk behavior of the tumor, patient needs to be monitored annually for lifelong. Conclusion: Pheochromocytoma is an uncommon tumor with varied clinical presentation. It can manifest itself widely from being silent to aggressive disease. This warrants high suspicion, early detection and management, thereby reducing the morbidity and mortality. Lately, there has been increased incidence of adrenal incidentalomas owing to widespread use of radiological investigations. We report a case of incidental pheochromocytoma which is biochemically active but clinically asymptomatic. This emphasizes the importance of being more vigilant during the evaluation of adrenal incidentalomas.