PSAT015 A Rare Case of Incidental Massive Pheochromocytoma with Ectopic Parathyroid Hormone Secretion

BACKGROUND: Pheochromocytoma (PC) is a rare neuroendocrine tumor with an annual incidence of 2 to 8 cases per million that can secrete excess catecholamines precipitating hyper-adrenergic symptoms. In rarer instances, PCs can also secrete substances other than catecholamines. CASE: A 51-year-old female underwent MRI lumbar spine that demonstrated an incidental 13 cm right adrenal mass. History was significant for newly diagnosed hypertension and a five-year history of episodic headaches, diaphoresis, palpitations and anxiety. A previous cardiac evaluation including Holter monitor, echocardiogram, and stress test was unrevealing. Physical exam was significant only for chronic back pain and BMI 20.4. Labs revealed elevated serum catecholamines with metanephrines and normetanephrines >40x and >65x the upper limit of normal respectively, elevated urine catecholamines and elevated chromogranin A suggestive of PC. Labs also demonstrated mild hypercalcemia >10.3 mg/dL (8.6-10.4 mg/dL) with elevated PTH 78 pg/mL (14-64 pg/mL) and low vitamin D 25-OH 25 ng/mL (30-100 ng/mL). Calcitonin, albumin and phosphorus were normal. She was treated with non-competitive alpha and beta-blockade and metyrosine before undergoing successful right adrenalectomy. Post-operative labs demonstrated normalization of catecholamines, PTH and calcium. Surgical pathology confirmed the diagnosis of PC and demonstrated tumor cells which stained for PTH confirming ectopic PTH secretion, a rare phenomenon. The PC was very large with an elevated PASS (Pheochromocytoma of the Adrenal Gland Scaled Score) indicating increased risk for malignancy/recurrence; however, there was low Ki-67 activity and no capsular involvement, which suggested benign behavior. Furthermore, an MIBG scan was negative for metastatic disease, and an extensive genetic workup for familial PC/PGL (including MEN, RET, SDHx) was negative. CONCLUSION: PC is a rare neuroendocrine tumor that can secrete excess catecholamines precipitating hyper-adrenergic symptoms and potentially fatal complications including hypertensive crises, cardiovascular disease, ischemia and multi-organ failure if untreated. Consequently, early recognition of PCs is imperative. The patient in this case had a five-year history of symptoms seen with PC and newly diagnosed hypertension despite normal BMI and negative cardiac workup. However, she had no evaluation for secondary causes of hypertension. Despite the large tumor size and significantly elevated catecholamines, she functioned without significant morbidity potentially due to adrenergic receptor desensitization. This case also highlights the rare phenomenon of ectopic secretion in PCs, specifically ectopic PTH secretion. A 2019 systemic review identified only 150 cases of pheochromocytomas/paragangliomas with ectopic hormone secretion – of those, only 17 secreted PTH or PTH-related peptide [1]. It is important to consider ectopic secretion in patients with PCs as they may have additional clinical manifestations associated with the hormone or substance secreted. Fortunately, this patient had no overt manifestations of hyperparathyroidism or hypercalcemia. REFERENCES: [1] Angelousi A, et al. Malignant pheochromocytomas/paragangliomas and ectopic hormonal secretion: case series and review of literature. Cancers. 05/2019;11(724). Presentation: Saturday, June 11, 2022 1:00 p.m. - 3:00 p.m.