What is the diagnosis and treatment for Pheochromocytoma (a type of adrenal gland tumor)?

From the Guidelines

Pheochromocytoma should be diagnosed and treated with a combination of biochemical testing, imaging studies, and surgical removal of the tumor, with proper preparation using alpha-blockers and beta-blockers to control blood pressure and prevent hypertensive crisis, as recommended by the most recent guidelines 1.

Diagnosis

The diagnosis of pheochromocytoma typically involves:

• Biochemical testing, primarily measuring metanephrines in blood or urine, with a sensitivity of 99% and specificity of 89% 1
• Imaging studies like CT, MRI, or specialized nuclear medicine scans such as MIBG to locate the tumor

Treatment

The definitive treatment is surgical removal of the tumor (adrenalectomy), but patients must be properly prepared with medication before surgery, including:

• Alpha-blockers like phenoxybenzamine (10-30 mg twice daily) or doxazosin (2-16 mg daily) started 1-2 weeks before surgery to control blood pressure
• Beta-blockers like propranolol (20-40 mg three times daily) only after adequate alpha blockade to prevent hypertensive crisis
• Calcium channel blockers like nifedipine may be added if needed

Post-Surgical Care

After surgery, patients require:

• Lifelong monitoring due to a 10-15% recurrence risk
• Genetic testing is recommended for all patients as about 30-40% of pheochromocytomas are associated with inherited syndromes like MEN2, VHL, or neurofibromatosis Some key points to consider in the management of pheochromocytoma include:
• The importance of proper preparation with alpha-blockers and beta-blockers to prevent hypertensive crisis
• The need for lifelong monitoring due to the risk of recurrence
• The recommendation for genetic testing to identify potential inherited syndromes It's worth noting that the management of pheochromocytoma may vary depending on the specific guidelines and recommendations, but the overall approach remains the same, with a focus on biochemical testing, imaging studies, and surgical removal of the tumor, with proper preparation and post-surgical care 1.

From the FDA Drug Label

INDICATION AND USAGE Phenoxybenzamine hydrochloride capsules are indicated in the treatment of pheochromocytoma, to control episodes of hypertension and sweating. If tachycardia is excessive, it may be necessary to use a beta-blocking agent concomitantly. The diagnosis of Pheochromocytoma is not directly stated in the label, but the treatment involves:

• Phenoxybenzamine to control episodes of hypertension and sweating
• Possible use of a beta-blocking agent if tachycardia is excessive 2

From the Research

Diagnosis of Pheochromocytoma

• The diagnosis of pheochromocytomas depends mainly upon the demonstration of catecholamine excess by 24-h urinary catecholamines and metanephrines or plasma metanephrines 3
• Computed tomography scan and magnetic resonance imaging of the adrenal glands and abdomen are used to localize the tumor, with complementary 123I-metaiodobenzylguanidine scintigraphy and 18F-dihydroxyphenylalanine-positron emission tomography available 3
• Screening for genetic alterations is important, as approximately one out of four pheochromocytomas turn out to be hereditary entities 3

Treatment of Pheochromocytoma

• Laparoscopic and adrenal sparing surgical intervention following preoperative alpha-blockade is the treatment of choice and usually curative 3
• Phenoxybenzamine is the commonly used alpha-adrenergic blocking agent, with therapy beginning with low doses and increasing stepwise up to 250 mg daily 4
• The optimal duration of preoperative therapy is 10 to 14 days, with efficiency of therapy judged by reduction of symptoms, stabilization of arterial blood pressure, and the presence of light orthostatic hypotension 4
• Beta-adrenergic receptor blockade with propranolol is indicated only after adequate alpha-adrenergic blockade in patients with tachycardia and catecholamine-induced arrhythmias 4, 5
• In malignant pheochromocytomas, radiotherapy and chemotherapy are palliative treatment options 3
• Alpha-methylparatyrosine (Metyrosine) is a new drug recently released for the treatment of pheochromocytoma when surgery is contraindicated or in cases of malignant pheochromocytoma 5
• Doxazosin is an alternative alpha-blocker that can be used in the preoperative treatment of pheochromocytoma, with some studies suggesting that it may have fewer side effects than phenoxybenzamine 6

Preoperative Management

• Preoperative management is crucial to prevent cardiovascular complications, with alpha-blockade being the mainstay of treatment 4, 7
• The use of an alpha-blocker is often accompanied by other vasoactive agents, with phenoxybenzamine often accompanied by a beta-blocker to control reflex tachycardia 6
• Perioperative haemodynamics seem to be slightly better controlled with phenoxybenzamine, at the cost of more pronounced postoperative hypotension 6