Pheochromocytoma is a very long word, even for someone who speaks "medical language." If you happen to be a fan of TV dramas involving young confused doctors, you may have heard the word a few times. It is made up of four parts: pheo-chromo-cyt-oma.
If you are one of the few people who have had a personal experience or know someone who has been suspected of having or has actually had a pheochromocytoma, I hope that this article helps explain what this big word actually means to patients and their families.
First, the basics and bit of anatomy is necessary to explain pheochromocytoma. Pheochromocytomas are tumors of the adrenal glands. As the name implies the ad-renal glands are located near the "renal" area. In other words, the adrenal glands are little glands that basically sit on top of the kidneys. One adrenal gland sits on top of each of the two kidneys.
Despite their small size, the adrenal glands do big things. They are complex endocrine (hormone secreting) glands. Depending on which area you focus on inside them, you find cells that do different things. There is an area where the cells secrete cortisol, a hormone similar to cortisone. There is another area where cells secrete a hormone called aldosterone which helps in water regulation.
And there is yet another area where the cells secrete substances called catecholamines -- epinephrine, norepinephrine and dopamine. These are "flight or fight" hormones. They are responsible in part for that feeling of an "ad-renal-ine" rush you feel when you are afraid. It is these cells that are involved in a pheochromocytoma. Basically, these cells secrete too much epinephrine, norepinephrine and dopamine, and that causes the clinical signs and symptoms we will discuss below.
Pheochromocytomas are, fortunately, quite rare and the vast majority of them are entirely benign. Only very rarely is a pheochromocytoma malignant.
What are the symptoms of a pheochromocytoma?
Someone with a pheochromocytoma usually has 3 classic symptoms -- headache, sweating, and heart palpitations (a fast heart beat).
When people go to their doctors with these symptoms, high blood pressure may be found. In some cases, the high blood pressure comes and goes and may be difficult to document. In other cases, the blood pressure is consistently elevated and easily recorded.
Pheochromocytomas, as I have mentioned, are not common. They are present in only about 0.2% of all people with high blood pressure. There are certain instances, however, where the diagnosis of pheochromocytoma may rank high on the list of possibilities.
What conditions are associated with pheochromocytomas?
Certain families have an increased risk of pheochromocytomas. The most common familial condition is called multiple endocrine neoplasia, or MEN for short. Two types of MEN -- MEN 2A and 2B -- are associated with pheochromocytomas. Both are genetic syndromes that run in families and are transmitted from parent to child in an autosomal dominant manner.
Pheochromocytomas are not the only tumors that occur in MEN 2A and 2B. MEN 2A carries an increased risk of tumors of the parathyroids, glands near the thyroid that help to regulate calcium. And both MEN 2A and 2B elevate the risk of thyroid cancer. In families where MEN is suspected, genetic testing can be done today to help identify family members at risk.
There are a number of other genetic disorders associated with pheochromocytomas. The most prominent is called von Hippel-Lindau syndrome. This disorder is rare but important because it is associated with the development of numerous benign and malignant tumors.
There are also many individuals who have pheochromocytomas with no known family history of them. These cases are termed sporadic. In general, if these patients have bilateral disease (pheochromocytomas in both adrenal glands) or are diagnosed before the age of 21, genetic screening is recommended.
What else can cause the symptoms of a pheochromocytoma?
Basically, anything that can cause overactivity of the sympathetic nervous system can be on the list to rule out when suspecting a pheochromocytoma. The sympathetic system is the main control panel governing the release of the "Flight or fight" response we talked about above. Things that can stimulate this include drugs (even excessive use of decongestants should be considered); withdrawal from drugs (such as suddenly stopping certain blood pressure medications); panic attacks attacks and spinal cord injuries can also lead to some of the symptoms seen in pheochromocytomas.
How do you make the diagnosis of a pheochromocytoma?
Pheochromocytoma is a possibility in anyone with the classic triad of symptoms -- headache, sweating, and heart palpitations -- especially when there is high blood pressure (though high blood pressure is not always seen, and to confuse things even further, low blood pressure can be found is certain cases too!). A physician becomes more suspicious if the patient is young and has no other risk factors or habits that may cause these findings.
Perhaps the patient knows their family history well and a doctor suspecting pheochromocytoma can go straight to genetic testing. However, in most cases, if suspicion is high, the physician proceeds with a series of tests to measure the culprit hormones and their break down products (metabolites).
First, hormones such as catecholamines and metanephrines are measured in a 24 hour urine collection and metanephrines may also be measured in the blood. If these are greater than 2 times the normal level, imaging studies are usually done to look at the adrenal glands.
If imaging of the adrenal glands shows a mass in the gland (or outside it), surgery may be done. If it is not clear that the mass is actually functional and related to the findings clinically, or if there is no mass seen on imaging, another test can be performed. This test called a 123-1MIBG scan is quite specific for pheochromocytomas.
How is a pheochromocytoma treated?
Surgery is the definitive treatment. Until the tumor is removed, control of blood pressure is a top priority. Controlling blood pressure before and during surgery is the trickiest part of care. There is a chance of developing an acute hypertensive crisis after anesthesia is given during the surgery. The blood pressure is therefore closely monitored through the procedure.
Because of the types of hormones involved in a pheochromocytoma, blood pressure control utilizes agents of a specific class of drugs known as alpha blockers. There are also certain drugs available which inhibit the formation of hormones by the tumor. These medications can be used if needed preoperatively.
In the rare instances of pheochromocytomas that are malignant, chemotherapy may be required after surgery.
What is the outlook with a pheochromocytoma?
Both malignant and benign pheochromocytomas can recur after surgery. The statistics vary from one study to the next but recurrence rates average around 10%. Therefore, long-term followup after surgery is very important.
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