About 85-90% of paragangliomas are intra-adrenal and the rest 10-15% are extra-adrenal(1).
The most common type of extra-adrenal paragangliomas is found in the head and neck region with carotid body paragangliomas being the most common type(2).
How To Diagnose Paragangliomas?
The diagnosis of paragangliomas is done both biochemically and image studies. The initial screening is done by measuring the 24-hour urine catecholamines and metanephrines and plasma free metanephrines. Certain medications, such as decongestants, tricyclic antidepressants, antipsychotic medications, amphetamines, levodopa, reserpine, acetaminophen, and ethanol can increase the level of catecholamines, thus giving a false-positive result. Therefore, it is necessary to make sure the patients are not taking the above medications at the time of screening(1).
When the biochemical screening tests are positive, they are further confirmed by imaging studies, such as abdominal MRI, CT scan, and 123-I meta-iodobenzyl-guanidine (MIBG). Other scans such as octreotide scan, whole-body MRI, and positron emission tomography (PET) scan may be done. Since paragangliomas are part of familial chromaffin-cell tumor syndromes, it is advised to get genetic testing done in patients who have been diagnosed with the tumor before the age of 40 years and with multiple tumors(1).
What Is The Best Medicine For Paragangliomas?
About 90% of the tumors are benign with only 10% being metastatic, so the best nature of treatment for benign paragangliomas is surgical resection. However, the tumor must be managed carefully before and during the surgery due to the risk of an episodic drop in blood pressure and an emergency increase in blood pressure. Before the surgery, management is aimed at blocking the alpha- and beta-adrenergic receptors and maintaining adequate volume. Volume status is maintained by administering intravenous fluids and advising a high salt diet to reduce the risk of an acute episode of low blood pressure(1).
It is also important to address the blockage of alpha-adrenergic receptors before beta-adrenergic receptors to reduce the chances of the acute hypertensive episode. Prazosin, phenoxybenzamine, or doxazosin are used as alpha-adrenergic receptors blockers to maintain the systolic blood pressure <120 mm Hg when seated and >90 mm Hg when standing; they are started 7-10 days before the scheduled surgery. Amlodipine, nicardipine, nifedipine, and metyrosine (for short term only) are used as beta-adrenergic blockers once alpha blockade is achieved(1).
The life expectancy of patients treated with surgical resection is equal to their non-tumor age-related counterparts(1).
Paragangliomas are catecholamine-secreting tumors of the chromaffin cell origin. These neuroendocrine tumors of the adrenal medulla are universally known as pheochromocytomas; whereas those outside the adrenal medulla are known as extra-adrenal pheochromocytomas or paragangliomas. Paragangliomas are found near the paraganglion of the autonomic nervous system, namely, the sympathetic nervous system and parasympathetic nervous system. Paraganglion is found anywhere from the base of the skull to the pelvis(1),(3).
Parasympathetic paragangliomas are found along the cranial and thoracic branches of the glossopharyngeal and vagus nerve. These sites include the carotid bodies, middle ear, larynx, subclavian region, cardiac and aortic region. Sympathetic paragangliomas are found in the abdomen, urogenital organs, urinary bladder, adrenals, and gallbladder. Paragangliomas can also be found in the liver, gut, pancreas, mesentery, thyroid, parathyroid, lung, heart, mediastinum, and pituitary. Paragangliomas of the head and neck region do not produce catecholamines (epinephrine, norepinephrine, dopamine), which is produced by the sympathetic paragangliomas(1),(2).
Clinical Representation Of Paragangliomas
Paragangliomas are rare with an incidence of 1.5-9 individuals per million per year. Intra-adrenal paragangliomas (pheochromocytomas) make up about 85-90% of the tumors while rest 10-15% are extra-adrenal tumors. The malignancy rate in paragangliomas and pheochromocytomas is around 10%, but paragangliomas associated with some familial syndromes have a malignancy rate as high as 50%(1).
The symptoms of paragangliomas are due to the secretion of hormones (epinephrine, norepinephrine, dopamine). The three classical symptoms of paragangliomas are tachycardia, episodic headache, and excessive sweating. Other less common symptoms include panic attacks, palpitations, shortness of breath, weight loss, hypotension on standing, and hyperglycemia(1).