What is pheochromocytoma?
Pheochromocytoma is a rare type of tumor that arises from certain cells known as chromaffin cells that produce hormones necessary for the body to function properly. Most pheochromocytomas arise from one of the two adrenal glands located above the kidneys at the back of the upper abdomen. Most chromaffin cells are located in the inner layer of the adrenal gland known as the adrenal medulla. About 90 percent of pheochromocytomas occur in the adrenal medulla.
The probability of development outside of this area is about 10 percent. These cases are called non-adrenal pheochromocytomas or paragangliomas. Paragangliomas can be found in the chest, heart, bladder, and neck or base of the skull. Symptoms associated with pheochromocytomas include high blood pressure (hypertension) , headaches , excessive sweating, or heart palpitations.
In most cases, this type of tumor occurs randomly (sporadically) for unknown reasons. In about 25 to 35 percent of cases, pheochromocytomas can be inherited as an autosomal dominant trait.
What causes pheochromocytoma?
Researchers do not know exactly what causes this type of tumor. The tumor develops in special cells called chromaffin cells located in the center of the adrenal gland. These cells secrete certain hormones, primarily adrenaline and noradrenaline, that help control many body functions such as heart rate, blood pressure, and blood sugar.
The role of hormones
Adrenaline and noradrenaline trigger your body’s fight-or-flight response to a perceived threat. Hormones cause your blood pressure to rise and your heart to beat faster. They prepare other body systems that allow you to react quickly. In the case of a pheochromocytoma, this causes more of the hormones to be released, causing them to be released even when you are not in a threatening situation.
While most chromaffin cells are found in the adrenal glands, small clusters of these cells are also found throughout the heart, head, neck, bladder, posterior abdominal wall, and spine. Chromaffin cell tumors, called paragangliomas, can cause the same effects on the body.
Who is at risk?
People with certain rare genetic disorders have an increased risk of pheochromocytoma or paraganglioma. Tumors associated with these disorders are more likely to be cancerous. These genetic conditions include:
- Multiple endocrine neoplasia type 2 is a disease that causes tumors in more than one part of the body’s hormone-producing (endocrine) system. Other tumors associated with this condition may appear in the thyroid, parathyroid, lips, tongue, and gastrointestinal tract.
- Von Hippel-Lindau disease can cause tumors in many regions, including the central nervous system, endocrine system, pancreas, and kidneys.
- Neurofibromatosis 1 results in multiple tumors of the skin (neurofibromas), patches of pigmented skin, and tumors of the optic nerve.
- Hereditary paraganglioma syndromes are inherited disorders that result in pheochromocytomas or paragangliomas.
What are the symptoms of pheochromocytoma?
In some cases, people with this type of tumor may not develop symptoms (asymptomatic). High blood pressure (hypertension) is the most common finding associated with pheochromocytomas. High blood pressure may persist or come and go.
Affected individuals may experience paroxysmal episodes, which are chronic episodes of high blood pressure that often cause headaches, irregular heartbeats (palpitations), and profuse sweating (diaphoresis). The frequency of these attacks varies from several times a day to several times a month.
The symptoms associated with pheochromocytomas occur due to the release of certain hormones (for example, norepinephrine and epinephrine) known as catecholamines. These hormones are released from chromaffin cells, which are part of the sympathetic nervous system.
The sympathetic nervous system controls certain involuntary activities in the body (for example, regulating the heartbeat or breathing rate, raising blood pressure). Excessive release of catecholamines causes high blood pressure and other characteristic symptoms of pheochromocytoma.
Additional, less common symptoms may include pain in the chest or abdomen , nausea, vomiting, diarrhea, constipation , pale skin (pale), weakness, and weight loss. Anxiety attacks may also occur.
Some people experience an extreme drop in blood pressure when they stand up suddenly, sometimes resulting in lightheadedness (orthostatic hypotension). In some cases, individuals with pheochromocytoma may have difficulties breaking down carbohydrates and develop diabetes .
If pheochromocytoma is left untreated, it can progress to serious, life-threatening complications such as heart muscle disease (cardiomyopathy), heart muscle inflammation (myocarditis), cerebral hemorrhage, or fluid buildup in the lungs (pulmonary edema). Some people with pheochromocytoma may be at risk of developing a stroke or heart attack (myocardial infarction).
About 10 to 15 percent of pheochromocytomas can be malignant. Extra-adrenal pheochromocytomas are more malignant than adrenal pheochromocytomas. Malignant pheochromocytomas can spread (metastasize) to various parts of the body, including the lymph nodes, liver, lungs, and bones.
When should you see a doctor?
Although high blood pressure is the primary manifestation of pheochromocytoma, most people with high blood pressure do not have an adrenal tumor. You should consult your doctor if any of the following factors apply to you:
- Difficulty controlling high blood pressure with current treatment
- Episodic worsening of high blood pressure
- Family history of pheochromocytoma
- A family history of a related genetic disorder
How is pheochromocytoma diagnosed?
Your doctor may order several tests, such as:
The following tests measure the levels of adrenaline, noradrenaline, or byproducts of these hormones in your body:
- 24-hour urine test: In this test, you take a urine sample each time you urinate over a 24-hour period. You will receive written instructions on how to store, label and return samples.
- Blood test: Your doctor will draw your blood to be tested in the laboratory.
If lab test results show you have a pheochromocytoma or paraganglioma, your doctor will order one or more imaging tests to find a possible tumor. These tests may include:
- Computed tomography: A CT scan is a specialized X-ray technology.
- Magnetic resonance imaging: MRI-emar is a technology that uses radio waves and a magnetic field to produce detailed images.
- M-iodobenzylguanidine imaging: A scanning technology that can detect an injected radioactive compound in small amounts ingested by pheochromocytomas or paragangliomas.
- Positron emission tomography: It is a scanning technology that can also detect radioactive compounds taken up by a tumor.
Imaging studies for other reasons
A tumor in the adrenal gland may be found during imaging studies for other reasons. In such cases, your doctor will usually order additional tests to determine the nature of the tumor.
Your doctor may recommend genetic testing to determine if pheochromocytoma is related to an inherited disorder. Information on possible genetic factors can be important for many reasons, such as:
- Because some inherited disorders can cause more than one condition, test results may indicate the need to screen for other medical problems.
- Because some disorders are more likely to be recurrent or cancerous, your test results may affect your treatment decisions or long-term plans to monitor your health.
- Results from your tests may suggest that other family members should be screened for pheochromocytoma or related conditions.
You can ask your doctor about genetic counseling services that can help you understand the benefits and results of genetic testing.
How is pheochromocytoma treated?
The primary treatment for pheochromocytoma is surgery to remove the tumor. Before surgery, your doctor will prescribe special blood pressure medications that block the action of high adrenaline hormones to reduce the risk of developing dangerously high blood pressure during surgery.
You will likely take two medications for 7 to 10 days before surgery that help lower blood pressure. These medicines will replace or add to other blood pressure medicines you are taking.
- Alpha blockers : These drugs keep smaller arteries and veins open and relaxed, improving blood flow and lowering blood pressure. Alpha blockers include phenoxybenzamine, doxazosin, and prazosin. Side effects may include irregular heartbeat, dizziness, fatigue, vision problems, male sexual dysfunction, and swelling in the limbs.
- Beta blockers: These drugs cause your heart to beat more slowly and with less force. They also help keep blood vessels open and relaxed. In preparation for your surgery, your doctor will likely prescribe a beta-blocker a few days after you start using an alpha-blocker. Beta-blockers include atenolol, metoprolol, and propranolol. Possible side effects include fatigue, stomach upset, headache, dizziness, constipation, diarrhea, irregular heartbeat, difficulty breathing, and swelling in the limbs.
- High-salt diet: Alpha and beta blockers dilate blood vessels, causing a decrease in the amount of fluid in the blood vessels. This can cause dangerous drops in blood pressure while standing. A high-salt diet prevents low blood pressure from developing during and after surgery by drawing more fluid into the blood vessels.
In most cases of pheochromocytoma surgery, your surgeon removes the entire adrenal gland with minimally invasive surgery. Your surgeon will open several small openings to insert wand-like devices equipped with video cameras and small instruments.
The remaining healthy adrenal gland performs the functions normally performed by the two glands. Blood pressure usually returns to normal.
In some cases, such as removal of the other adrenal gland, your doctor may simply remove the tumor and preserve some healthy tissue.
If a tumor is cancerous, the tumor and other cancerous tissue will be removed. However, even if not all of the cancerous tissue is removed, surgery can limit hormone production and provide some blood pressure control.
Very few pheochromocytomas are cancerous. Therefore, research on the best treatments is limited. Cancerous tumors that spread throughout the body associated with pheochromocytoma and cancer treatments include:
- M-iodobenzylguanidine therapy: This treatment is also an imaging technology in which a radioactive iodine that adheres to adrenal tumors is injected. The goal of treatment is to apply radiation therapy to a specific area and kill the cancerous cells.
- Peptide receptor radionuclide therapy: This treatment combines a drug that targets cancer cells with a small amount of radioactive material. It allows radiation to be delivered directly to cancer cells.
- Chemotherapy: Chemotherapy is the use of powerful drugs that kill fast-growing cancer cells.
- Radiation therapy: This can be used, for example, for the symptomatic treatment of tumors that have spread to the bone causing pain.
- Targeted cancer treatments: These drugs inhibit the function of naturally occurring molecules by promoting the growth and spread of cancerous cells.