Pheochromocytoma or Feocromocitoma: Description:
A functional chromaffinoma, usually benign, derived from adrenal medullary tissue cells and characterized by the secretion of catecholamines, resulting in hypertension, which may be paroxysmal and associated with attacks of palpitation, headache, nausea, dyspnea, anxiety, pallor, and profuse sweating. Pheochromocytoma is often hereditary, not only in phacomas such as Hippel-Lindau disease, neurofibromatosis, and familial endocrine neoplasia, but also as an isolated defect [MIM*171300] as an autosomal dominant trait. See Also: paraganglioma.
A pheochromocytoma is a rare tumor that develops in the core of an adrenal gland. You have two adrenal glands, one just above each of your kidneys. They produce hormones called catecholamines. The most important of these are adrenaline (epinephrine) and noradrenaline (norepinephrine). Your body needs these hormones to maintain blood pressure and to help cope with stressful situations. Physical and emotional stresses usually trigger their release. When secreted into your bloodstream, catecholamines increase your heart rate and blood pressure and affect several other body functions.
Pheochromocytomas are catecholamine producing tumors of chromaffin cells, that can occur sporadically or as part of a familial syndrome. Although the majority are found in the adrenal glands, pheochromocytoma can basically be found wherever chromaffin tissue can be found. 97% have been found in the abdomen, 2% in the thorax and 1% in other regions.
Pheochromocytomas can be found anywhere in the body, though most occur in the adrenal medulla. Even a tiny benign pheochromocytoma can make a person very sick. Regardless of location and appearance, the patients will usually report anxiety, headache, palpitations, panic attacks, sweating, and dizziness as some of the main symptoms. Extra-adrenal paragangliomas (often called extra-adrenal pheochromocytomas) are closely related and less common tumors. These tumors originate in the ganglia of the sympathetic nervous system and are named based upon the primary anatomical site of origin.
It is estimated that approximately ten to twenty-five percent of pheochromocytoma cases are genetic. There are a number of these genetic types of conditions, including Multiple Endocrine Neoplasia Syndromes, Von Hippel-Lindau, Von Recklinghausen's Neurofibromatosis, Succinic Dehydrogenase Mutation.
Histologically, pheochromocytoma is composed of large pleomorphic chromaffin cells. Electron microscopy reveals electron-dense neurosecretory granules. Approximately 10% of pheochromocytomas are considered to be malignant. No histologic features exist that distinguish benign from malignant tumors. Microscopic evidence for local invasion of tissue or blood vessels, however, suggests malignancy. Criteria based on tumor size, mitotic index, and DNA ploidy have been reported to be helpful in some series, though they are not always reliable predictors of biologic behavior. Because the distinction between benign and malignant tumors cannot be made with certainty, careful surveillance is needed for a prolonged period after the initial surgical resection.
The hypertension caused by pheochromocytoma may be sustained or paroxysmal and is often severe with occasional malignant features of encephalopathy, retinopathy, and proteinuria. Less commonly, severe hypertensive reactions may occur during incidental surgery, following trauma, exercise, or micturition (in the setting of bladder pheochromocytoma) when the diagnosis is unsuspected. Other clinical features of pheochromocytoma include headache, sweating, palpitation, tachycardia, and severe anxiety along with epigastric or chest pain. Orthostatic hypotension is frequently present and is probably caused by reduced intravascular volume following chronic adrenergic stimulation.
Genetic testing: Genetic mutations may be responsible for pheochromocytoma and paraganglioma, and your doctor may suggest genetic testing. However, whether you need genetic testing and, if so, which type depends on the location of your tumor and related medical conditions. If you have a history of pheochromocytoma or an associated disease, seek genetic counseling to help you decide if you should undergo genetic testing.
Causes and Risk factors:
Researchers don't know exactly what causes cells within the adrenal gland to develop into a tumor. What they do know is that pheochromocytomas begin in special cells called chromaffin cells, which are found in the core of the adrenal gland. Your adrenal glands are part of your endocrine system, which produces hormones that regulate processes throughout your body.
Your adrenal glands are located on top of your kidneys, and they produce hormones called catecholamines. The most important of these are adrenaline (epinephrine) and noradrenaline (norepinephrine). Your body needs these hormones to maintain blood pressure and to help cope with stressful situations. Physical and emotional stresses usually trigger their release. When secreted into your bloodstream, catecholamines increase your heart rate and blood pressure and affect several other body functions.
In most cases, both genetic and environmental factors play a role. The condition can occur alone or in combination with other disorders. The following are the most common disorders associated with pheochromocytoma:
Von Hippel-Lindau disease.
Multiple endocrine neoplasia (MEN) syndromes.
An examination of vital signs can show high blood pressure, rapid heart rate, and fever when taken during an attack of symptoms. These signs can be normal at other times.
The diagnosis of pheochromocytoma is established by the demonstration of elevated 24-hour urinary excretion of free catecholamines (norepinephrine and epinephrine) or catecholamine metabolites (vanillylmandelic acid and total metanephrines). The measurement of plasma catecholamines can also be of value in the diagnosis of pheochromocytoma. The measurement of plasma catecholamines, however, has limited sensitivity and specificity. Plasma metanephrines have been reported to be more sensitive than plasma catecholamines. Pharmacologic testing with agents such as glucagon or clonidine is rarely required to make the diagnosis.
Abdominal CT scan.
Catecholamines in the blood.
MIBG (metaiodobenzylguanidine) scintiscan.
MRI of abdomen.
Blood and urine tests (to measure hormone levels).
Radioisotope Scan - uses radioactive substances introduced into the body to create an image of the functioning adrenal glands.
Once a diagnosis of pheochromocytoma has been established and the tumor located, surgical removal of the tumor is standard treatment if possible. This is not always as simple as it sounds. Some patients with pheochromocytoma find that it is difficult for the location of the tumor to be discovered. There are also cases of "quiet" pheochromocytomas which take longer to find and remove. For pheochromocytoma surgery, it is vital to ask your surgeon how many patients he or she has operated on specifically for this type of tumor. The most common treatment for a pheochromocytoma is surgical removal of the entire affected adrenal gland. In most cases, signs and symptoms then disappear. Blood pressure usually returns to normal soon after surgery. Before surgery, your doctor will prescribe medications to block the effects of the adrenal hormones and control blood pressure. If both adrenal glands are affected by pheochromocytoma and are surgically removed, you'll need to take medication to replace the other hormones once produced by these glands. Continuous medical follow-up may be required to monitor the development of future tumors.
Depending on the size and location of the tumor, laparoscopic surgery may be performed. Laparoscopic surgery involves inserting instruments through several small incisions. This procedure may result in quicker recovery when compared with conventional surgery, which requires a larger incision. Laparoscopic surgery isn't for everyone, however. Talk to your doctor about this less invasive technique to see if it's an option for you.
Sometimes surgery isn't an option because of the way the tumor is growing or because the tumor has spread (metastasized) to other parts of your body. If a pheochromocytoma is cancerous (malignant), treatment may go beyond medication and surgery to include radiation, chemotherapy or destroying the function (ablation) of arteries that supply blood to the tumor.
Medicine and medications:
Medications used to treat high blood pressure associated with pheochromocytomas include:
Alpha blockers: Alpha blockers, also called alpha-adrenergic blocking agents or alpha-adrenergic antagonists, relax certain muscles that help small blood vessels remain open. They work by keeping the hormone noradrenaline (norepinephrine) from stimulating the muscles in the walls of smaller arteries and veins. This stimulation makes the vessel walls constrict. Blocking that effect causes the vessels to remain open and relaxed. This improves blood flow and lowers blood pressure. Examples of alpha blockers include phenoxybenzamine (Dibenzyline), doxazosin (Cardura), prazosin (Minipress) and terazosin (Hytrin).
Beta blockers: Beta blockers, also known as beta-adrenergic blocking agents, make your heart beat more slowly and with less force. They work by blocking the effects of the hormone norepinephrine. This action slows down the nerve impulses that travel through your heart. That means your heart doesn't pump as hard because it needs less oxygen and blood. Beta blockers also slow down the release of the enzyme renin from your kidneys, helping keep blood vessels dilated. Examples of beta blockers include atenolol (Tenormin), metoprolol (Lopressor, Toprol XL) and propranolol (Inderal LA).
Note: The following drugs and medications are in some way related to, or used in the treatment. This service should be used as a supplement to, and NOT a substitute for, the expertise, skill, knowledge and judgment of healthcare practitioners.
DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.
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