Pheochromocytoma
Overview
Pheochromocytoma is a rare but classic board-favorite endocrine tumor that shows up on the PANCE because missing it in real life can be dangerous—and missing it on the exam costs easy points.
Let’s break it down the way the PANCE expects you to know it.
Pathophysiology
Pheochromocytoma is a catecholamine secreting endocrine tumor arising from a the chromaffin cells of the adrenal medulla. These tumors are typically benign and produce excess amounts of epinephrine and norepinephrine leading to episodic or sustained sympathetic overstimulation. If undiagnosed can become life-threatening. Approximately 90% of these tumors are benign with 10% being malignant and may be associated with MEN syndrome IIa/IIb.
Clinical Manifestation
The most common sign of pheochromocytoma is hypertension refractory to medication management. Additionally we utilize the rule of the 3 H’s for symptom recognition which include 1) Headache 2) Hyperhidrosis 3) Heart Palpitations/Tachycardia. Patients may also present with chest or abdominal pain, weakness, fatigue, and weight loss.
Diagnosis
Obtaining the diagnosis of pheochromocytoma can be made using serum and urine tests. A 24-hour urine catecholamines and metabolite collection is generally the first line testing, however, obtaining serum free metanephrines has a superior sensitivity value that urine. Findings that would support your suspicion for pheochromocytoma are grossly high levels of catecholamines and their metabolites including metanephrines and vanillylmandelic acid.
Once lab values support a possible diagnosis an abdomen MRI/CT is used to visualize tumor size and location. Other labs that may be elevated include hyperglycemia and hypokalemia. If MENIIa/IIb is suspected measuring serum calcitonin levels and genetic testing may be indicated.
Treatment
Surgical resection of the tumor stands as the definitive treatment for pheochromocytoma. If hypertension control is warranted prior to surgical resection pre-operative Alpha blockade with Phenoxydenzamine or Phentolamine is necessary rather than Beta blockers. This is due to avoid excess Alpha-mediated vasoconstriction and hypertension caused by catecholamine release during manipulation and resection of the tumor. After successful removal Beta blockers, such as propranolol, may used for control of tachyarrhythmias postoperatively.
Quiz Question
A 34-year-old woman presents to the clinic with episodic headaches, palpitations, and excessive sweating for the past 6 months. Her blood pressure during today’s visit is 178/102 mmHg, though she reports normal readings between episodes. CT scan reveals a 3.5-cm adrenal mass. Which of the following is the most appropriate next step in management?
A. Start propranolol therapy
B. Start phenoxybenzamine therapy
C. Proceed directly to surgical resection
D. Perform percutaneous biopsy of the adrenal mass
E. Begin ACE inhibitor therapy
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The correct answer is B. start pheoxybenzamine therapy