Pheochromocytoma Masquerading as Weight Loss - a Diagnostic and Management Challenge

Abstract

Abstract Introduction: Classic pheochromocytoma symptoms include headache, diaphoresis, palpitations and symptomatic pheochromocytomas are on average around 5cm. They respond to preoperative alpha blockade followed by surgery. We present a case of a giant 15.9cm pheochromocytoma with delayed presentation and diagnosis complicated by atypical symptoms of nausea, weight loss; preoperative preparation included a modified preparation of high-dose phenoxybenzamine but she underwent successful surgery. Case Description: A 62-year-old female with a history of hypertension and diabetes presented with nausea and 80 lbs weight loss over 18 months. CT scan revealed large centrally necrotic mass overlying the left kidney, measuring 15.9 x 12.7 x 14.7cm. Abdominal MRI showed claw sign; she was admitted to the urology service for tube feeding prior to resection of suspected renal cell carcinoma. Given the location of the mass and history of hypertension, plasma metanephrines, included in preoperative workup, were notable for: total metanephrines >40000 pg/ml (reference range <=205), normetanephrines >20000 pg/ml (reference range <=148), metanephrines 57 pg/ml (reference range <=57). Endocrine was consulted and she was started on phenoxybenzamine; she underwent volume replacement with fluids and salt tablets. Due to nausea and vomiting she was unable to reliably tolerate oral medication; BP management was challenging. Oral pill dosing was minimized. Metoprolol was converted to metoprolol SA and a phenoxybenzamine suspension that could be delivered through the feeding tube with good absorption was made. On the day prior to surgery, BP was 117/76 mmHg, supine HR 92 bpm, on a total daily dose of phenoxybenzamine 240mg, metoprolol SA 200mg and amlodipine 10mg. She underwent a radical left nephrectomy and adrenalectomy. Plasma metanephrines six weeks later were normal: total metanephrines 84 pg/ml, normetanephrines 84 pg/ml, metanephrines <25 pg/ml. Pathology showed benign pheochromocytoma. Conclusion: Giant pheochromocytomas present significant challenges for clinicians who must be aware of the potential for nonspecific symptoms which can delay diagnosis. Paroxysmal hypertension happens in only about 50% of pheochromocytoma patients; primary hypertension is often diagnosed, as had been the case with our patient. Additionally, initial imaging related to atypical presenting symptoms may not lead to the specific diagnosis, as in our patient; metanephrine screening revealed the correct diagnosis. Regarding management, preoperative alpha blockade dosage and delivery should be tailored to individual patient needs, with adjustment as needed and alternative preparations considered to optimally control BP and reduce risk of death and other perioperative complications. Our case highlights the diagnostic and management challenge of patients presenting with giant pheochromocytomas.