MON-396 Biochemically Silent Adrenal Mass in a Hypertensive Female

We describe a case of a biochemically silent pheochromocytoma, which raises the question about the appropriate pre-operative approach in cases of biochemically “silent” adrenal tumors. A 37-year-old white female was referred to our endocrinology clinic for evaluation of a large right sided adrenal incidentaloma. She was symptomatic for episodic severe migratory headaches, dizziness, intermittent orthostasis and anxiety. She was being treated for hypertension with labetalol 200mg twice daily. She denied any family history of pheochromocytomas or adrenal tumors. Her physical examination was unremarkable apart from BP 191/115, with regular heart rate of 93 beats per minute. Her BMI was 19 and she did not exhibit any cushingoid features. She had undergone biochemical testing 17 months prior, which included 24 hour urine fractionated metanephrines and catecholamines, 1mg overnight dexamethasone suppression test and aldosterone level, all of which were unremarkable. Biochemical work-up was again repeated and included fractionated metanephrines <0.20nmol/L (normal <0.50nmol/L), normetanephrines <0.70nmol/L (normal <0.90nmol/L), aldosterone 16ng/dl (normal <21ng/dl), renin activity 3.8ng/ml/hr (0.6-4.3ng/ml/hr), late night salivary cortisol <50ng/dl (normal <100ng/dl), total testosterone 26ng/dl (14-76ng/dl) and DHEA-S 3.1ng/ml (normal <10ng/ml). Results were consistent with a non-functional adrenal tumor. CT imaging was remarkable for 8.0 x 7.5 x 7.0 cm well defined heterogeneous solid and cystic mass involving the right adrenal gland, the central necrotic portion of the mass showed no enhancement, whereas the peripheral solid portion of the mass showed progressive enhancement with HU values of 50, 67 and 75 on unenhanced CT, arterial phase and portal venous phase respectively and no wash out findings. Patient was started on an alpha blocking agent with dramatic improvement in her blood pressure perioperatively. She underwent successful open right sided adrenalectomy. Pathology was remarkable for a pheochromocytoma. Pheochromocytomas are rare neuroendocrine tumors originating from chromaffin tissue, which can be associated with significant morbidity and mortality. It is not uncommon for these tumors to be clinically silent but it is rare for them to be biochemically silent. This case highlights the importance of reviewing the adrenal imaging phenotype and following clinical suspicion and treating perioperatively as a pheochromocytoma, despite a negative biochemical work-up. If untreated perioperatively with adequate alpha blockade, these cases can result in a perioperative hemodynamic instability, adrenergic crisis and potentially death.