SAT-506 - Management of Biochemically Silent Pheochromocytomas and Implications for Surgical Practice in Von-Hippel-Lindau Syndrome

Hypertensive crisis in pheochromocytomas is a life-threatening elevation in blood pressure that can result in complications such as myocardial infarction, stroke, arrhythmias, and pulmonary edema. This applies to all pheochromocytomas, including biochemically silent pheochromocytomas (BSP), which can still release catecholamines during surgical manipulation despite normal baseline levels. We present the case of a 46-year-old female patient with a medical history of von Hippel-Lindau (VHL) syndrome who came to the Endocrinology Clinic for evaluation of bilateral adrenal adenomas. These lesions were discovered as part of screening studies typically performed in patients with VHL approximately 4 years ago. An abdominopelvic CT scan with an adrenal protocol revealed two adrenal lesions: one on the right adrenal gland that measured 3.3 cm x 3.0 cm x 3.0 cm, and one on the left adrenal gland that measured 2.3 cm x 2.2 cm x 2.3 cm. Both were described as heterogeneous enhancing masses, with small areas of necrosis that were concerning for pheochromocytomas. Workup, including 24-hour urine catecholamines and plasma metanephrines, was negative. The patient denied symptoms related to pheochromocytoma spells, such as pallor, hypertension, palpitations, and headaches. She had been diagnosed with VHL at a young age and already had multiple clinical manifestations associated with this condition. Family history was pertinent for VHL in her grandmother, mother, and daughters, all of whom had prior history of adrenalectomies. Biochemically silent pheochromocytomas represent 15% of pheochromocytomas and are often discovered incidentally on imaging. The underlying mechanism is complex and varies; some tumors may have defective catecholamine synthesis due to tyrosine hydroxylase mutations, defects in secretion, and chromaffin alterations. However, these tumors may still precipitate an adrenal crisis with certain triggers, such as anesthesia for adrenalectomies. For this reason, pre-operative alpha-adrenergic blockade for 7 to 14 days before surgery was performed in this patient. In the absence of hypertension, we started with low-dose Doxazosin at 1 mg PO daily and did not have to increase the dose during the pre-operative period. After successful alpha-blockade, we initiated beta-adrenergic blockade with low-dose propranolol to achieve a resting heart rate of 80 beats per minute. The patient underwent right adrenalectomy, and the left side lesion was located extra-renal. Later, pathology confirmed the presence of a right pheochromocytoma and a left paraganglioma. The patient tolerated the procedure well without complications. She now undergoes yearly surveillance with imaging and laboratory tests. Recognizing BSP’s prevents the potential risk of hypertensive crisis during major surgeries, as this can reduce complications and lower morbidity and mortality in patients.

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