What is pheochromocytoma (a type of tumor that affects the adrenal glands)?

From the Guidelines

Pheochromocytoma is a rare tumor that develops in the adrenal glands, causing them to produce excessive amounts of catecholamines, and the best approach to managing it is surgical removal of the tumor, as recommended by the most recent guideline 1.

Key Characteristics of Pheochromocytoma

• Pheochromocytomas are characterized by increased blood pressure variability, which constitutes an additional independent risk factor beyond increased blood pressure itself for cardiovascular morbidity and mortality, as noted in studies 1.
• These tumors typically cause symptoms like high blood pressure, headaches, sweating, and heart palpitations that occur in episodes or "attacks."
• The diagnosis of pheochromocytoma should be entertained in a hypertensive patient with a combination of headaches, palpitations, and sweating, typically occurring in an episodic fashion, with a diagnostic specificity of 90% 1.

Diagnosis and Screening

• The best screening test for pheochromocytoma is plasma free metanephrines (normetanephrine and metanephrine), which carries a 99% sensitivity and an 89% specificity 1.
• Diagnosis involves measuring catecholamines or their metabolites in urine or blood, followed by imaging studies like CT scans or MRI to locate the tumor.

Treatment and Management

• The definitive treatment is surgical removal of the tumor, which requires careful pre-operative management with alpha-blockers (like phenoxybenzamine) for 1-2 weeks, followed by beta-blockers (like propranolol) if needed for tachycardia, as this sequence is crucial to avoid dangerous blood pressure elevations.
• About 10% of pheochromocytomas are malignant, and approximately 25% occur as part of inherited syndromes like Multiple Endocrine Neoplasia type 2 or Von Hippel-Lindau disease, making genetic testing important for some patients 1.
• After surgery, patients require lifelong monitoring as recurrence is possible, with follow-up testing of catecholamine levels recommended annually for at least 10 years.
• For patients with multifocal disease, including head and neck paragangliomas (HNPGLs), functional PPGLs should be resected as an initial priority, and patients should be offered appropriate surgical consultation with an experienced surgeon 1.

From the Research

Overview of Phaeocromocytoma

• Phaeocromocytoma is a rare catecholamine-producing neuroendocrine tumor, with the majority arising from the adrenal medulla 2.
• The usual presenting features of phaeocromocytoma include paroxysmal hypertension, sweating, headaches, and palpitation 2.
• Gene mutations are reported in 32-79% of cases, making genetic screening mandatory in all cases 2.

Diagnosis of Phaeocromocytoma

• Measurement of plasma or 24-hour urinary fractionated metanephrines is the best biochemical diagnostic test 2.
• Computed tomography or magnetic resonance imaging has high sensitivity (90-100%) and reasonable specificity (70-90%) for anatomical localization 2.
• Radionuclide imaging modalities such as metaiodobenzylguanidine (MIBG) scintigraphy, positron emission tomography, or single photon emission computed tomography are used to assess functionality 2.

Treatment of Phaeocromocytoma

• The only modality of curative treatment is tumor excision 2.
• Preoperative treatment with an alpha-blocker, such as phenoxybenzamine or doxazosin, is used to prevent hemodynamic instability during surgery 3, 4.
• Phenoxybenzamine may blunt intraoperative hypertension better than doxazosin, but this difference did not translate to fewer cardiovascular complications and is offset by a considerably increased cost 4.
• Beta-adrenergic receptor blockade with propranolol is indicated only after adequate alpha-adrenergic blockade in patients with tachycardia and catecholamine-induced arrhythmias 5.

Management of Phaeocromocytoma

• The fundamental principles of phaeocromocytoma management include a high index of clinical suspicion, biochemical confirmation of the diagnosis, preoperative localization and pharmacologic treatment, meticulous anesthesia and intraoperative cardiovascular monitoring, and attention to surgical principles 6.
• For malignant lesions, pharmacologic management, teleradiotherapy, radiopharmaceutical treatment, and chemotherapy may be used 6.
• Annual follow-up with clinical and biochemical assessment is recommended in all cases after treatment 2.