Serendipity and the Second Malignancy: Clear Cell Renal Carcinoma Workup Revealing a Paraaortic Paraganglioma With Post-Operative Vasoplegia

Pheochromocytoma and paraganglioma (PPGL) are neuroendocrine tumors requiring careful pre- and post-operative management to dampen fluctuations in catecholamines. These lesions are not typically biopsied due to risk of catecholamine-induced hemodynamic instability. This case illustrates the importance of considering PPGL in patients without typical symptoms, and highlights challenges with post-operative blood pressure management following use of phenoxybenzamine. A 52 year old man presented with a 40 lb weight loss. PET/CT revealed a right renal mass, enlarged retroperitoneal lymph nodes, and increased uptake in retroperitoneal and paraaortic lesions. Paraaortic lymph node biopsy was consistent with paraganglioma. This finding was unexpected as the patient did not report palpitations, paroxysmal hypertension, or diaphoresis. He had no family history of neuroendocrine tumors. Fortunately, he had no adverse effects during biopsy despite subsequent testing showing elevated plasma metanephrines (271 pg/mL, normal ≤ 57 pg/mL) and normetanephrines (770 pg/mL, normal ≤ 148 pg/mL). I-123 MIBG scan revealed an enlarged left paraaortic mass with increased activity consistent with paraganglioma. He started preoperative alpha blockade with phenoxybenzamine 14 days prior to surgery. Propranolol was added 10 days later to provide combined sympathetic blockade. The patient underwent partial right nephrectomy and resection of the paraaortic mass. Pathology showed renal cell carcinoma (RCC) and paraganglioma, respectively. On post-operative day 1, maintenance fluids were discontinued and he developed palpitations and tachycardia to 140 beats per minute, with blood pressure in the 130s/80s. RCC associated pulmonary embolism, beta-blocker withdrawal, and vasoplegia due to phenoxybenzamine use and paraganglioma resection were considered. The patient was treated with 4 additional liters of normal saline over the next two days to address post-operative vasoplegia, and his tachycardia resolved. Genetic testing for neuroendocrine tumor syndromes including Von Hippel-Lindau (VHL) is ongoing. Clinical Lessons: 1. PPGL should be considered in patients with newly identified intraabdominal masses, even in patients without typical symptoms of catecholamine excess to avoid high risk biopsy. 2. Paraganglioma resection is associated with vasoplegia due to post-operative reduction in circulating catecholamines. 3. The covalent, irreversible alpha antagonist phenoxybenzamine accumulates in adipose tissue, and clinical effects can last up to 7 days after discontinuation. Hypotension can be avoided with aggressive fluid resuscitation. Beta antagonists should be used with caution as they may precipitate hypotension. 4. For patients presenting with paraganglioma and renal cell cancer, genetic syndromes including VHL or RAPTAS etiologies should be considered.