Pheochromocytoma (Pheo) of the Adrenal Gland

What are Pheochromocytomas and Paragangliomas?

Pheochromocytomas are tumors of the adrenal gland that produce excess adrenaline-type hormones, called catecholamines (epinephrine, norepinephrine, and dopamine). Pheochromocytomas arise from the central portion of the adrenal gland, which is called the adrenal medulla. The adrenal medulla is responsible for the normal production of adrenaline, which our body uses to help maintain blood pressure and to cope with stressful situations. A tumor that arises from the adrenal medulla and overproduces these hormones is called a pheochromocytoma, or pheo, and it can be a deadly tumor because of the severe elevation in blood pressure it causes.

Paragangliomas are tumors that are nearly identical to pheochromocytomas except that these tumors grow outside of the adrenal gland (pheos are, by definition, always inside the adrenal gland). Paragangliomas most often occur inside the abdomen, in the retroperitoneum (the back side of the abdomen), close to the big vessels, the aorta, and the inferior vena cava, but they can also arise in the pelvis (including the bladder), the chest, and the head and neck. Many of the symptoms and treatments are the same as for pheochromocytomas. Read about the differences between pheochromocytoma and paraganglioma on our blog; this page deals with pheochromocytomas.

Although most pheochromocytomas never spread, these tumors are highly toxic, and sometimes deadly, due to the secretion of adrenaline-type hormones. The most common causes of complications and death are the effects of these hormones on the heart, blood vessels, and brain: sustained or episodic hypertension (high blood pressure), stroke, heart attack, heart arrhythmias, congestive heart failure, shock lung, low blood pressure and fainting. We diagnose and treat these tumors regularly. Unfortunately, it is not uncommon that a pheochromocytoma is not diagnosed until the patient is admitted to the intensive care unit (ICU) with some of these devastating complications. This is sometimes called an adrenergic crisis or pheochromocytoma crisis. Often, when looking back at their medical history, patients have had symptoms for years or even decades.

---

Is Pheochromocytoma Still the "10% Tumor"? Why the Rule of 10s Is Outdated

You may still read that pheochromocytoma is the "ten percent tumor" (10% hereditary, 10% malignant, 10% bilateral, 10% outside the adrenal, 10% in children). This old "rule of 10s" is outdated and should no longer be used. Here is what we know today:

What We Now Know About Pheochromocytomas:
• Hereditary: about 30–40% are caused by an inherited gene change, far more than 10%. This is why genetic testing should be offered to every patient, whatever their age or family history.
• Metastatic potential: pheochromocytomas are no longer divided into "benign" and "malignant". Most never spread, but every one has some potential to spread (metastasize). The risk is higher for paragangliomas and for people with a change in the SDHB gene.
• Bilateral (in both adrenal glands): uncommon in people without an inherited syndrome, but common in hereditary syndromes such as MEN2 and von Hippel-Lindau (VHL) disease.
• Extra-adrenal (outside the adrenal glands; these are called paragangliomas): more common than the old 10% figure.
• In children: about 10–20% of cases are found in children and teenagers, and most of these are hereditary.
• Recurrence: a pheochromocytoma can come back, or a new one can form, many years later. This depends mainly on the inherited gene and on whether any adrenal medulla tissue remains, which is why follow-up with a yearly metanephrine test is lifelong.
• Silent: some pheochromocytomas cause no symptoms and normal blood pressure and are found by accident on a scan. In our center's published series, about 15% of non-hereditary pheochromocytomas were silent.

Here's a look at the extra-adrenal sites (locations NOT in the adrenal, and therefore called "paragangliomas"):

• Within the sympathetic nerve chain along the spinal cord
• Alongside the aorta (the main artery from the heart) in the abdomen
• Within the urinary bladder
• In the chest, and in the head and neck (these often do not make hormones)
• Remember, the large majority of these tumors are in the adrenal glands

---

Are Pheochromocytomas of the Adrenal Gland Rare?

Yes, pheochromocytomas are rare tumors, although more are being found today because so many people have scans for other reasons. They are not rare for us: we see patients with pheochromocytomas regularly, and patients with extra-adrenal paragangliomas (which are rarer) less often. The diagnosis is easy to miss because 1) the symptoms come and go, 2) many patients do not feel sick, or only occasionally have symptoms, and 3) the symptoms are highly individual and variable. Pheochromocytoma has been called the great “mimicker” because its symptoms mimic those of many other diseases. The most common sign is high blood pressure, which is often not investigated further and is simply treated with blood pressure pills (anti-hypertensives).

Who Gets Pheochromocytomas?

Pheochromocytomas affect men and women equally, and are most commonly diagnosed in middle-aged individuals. However, pheochromocytomas can occur in children and adolescents as well as in very old patients. About 30–40% of pheochromocytomas and paragangliomas are hereditary (meaning they occur in families because of an inherited change in a tumor-susceptibility gene), and hereditary tumors often occur at an earlier age. For this reason genetic testing and counseling should be offered to every patient with a pheochromocytoma or paraganglioma, and family members of a person who carries one of these gene changes should be tested as well. In some hereditary syndromes, such as multiple endocrine neoplasia type 2 (MEN2), a person who carries the gene change has about a 50% risk of developing a pheo during their lifetime. Learn more on our pheochromocytoma genetics page.

Who Should Be Tested for Pheochromocytoma and Paraganglioma?

Fortunately, testing for pheochromocytomas and paragangliomas is simple. The test measures metanephrines (metanephrine and normetanephrine), which are the breakdown products of the adrenaline-type hormones. This is done with a blood test (plasma free metanephrines) or a 24-hour urine collection (urine fractionated metanephrines). Read more about blood and urine tests for pheochromocytoma.

If you have some of these symptoms or if you belong to any of the following groups, you need to be tested to make sure you do not have a pheochromocytoma.

• Hypertension at a young age.
• An adrenal incidentaloma (an adrenal mass found by accident on a scan), whether or not you have high blood pressure.
• High adrenaline “spells”. These are very variable but may include palpitations (heart racing and pounding), pallor (the face turning pale, often followed by flushing), tremor (shakiness), headache, and sweating.
• Spells may be spontaneous or precipitated by change in body position, anxiety, medications (e.g., metoclopramide, anesthetic agents), and maneuvers that increase intraabdominal pressure (e.g. going to the bathroom).
• Hypertension in a family with any family member with an adrenal tumor (pheochromocytoma/paraganglioma).
• Resistant hypertension (i.e. poor response to medications).
• Hypertension requiring many medications.
• Hypertension and a family history of early-onset (before 50 years of age) hypertension or stroke at a young age.
• Hypertension that is episodic (paroxysmal).
• A familial syndrome that predisposes to catecholamine-secreting tumors (e.g., multiple endocrine neoplasia type 2, neurofibromatosis type 1, von Hippel-Lindau disease, familial pheochromocytoma & paraganglioma syndromes).
• A sudden, marked rise in blood pressure during anesthesia, surgery, or angiography.
• Unexplained (idiopathic) dilated cardiomyopathy (enlargement and weakening of the heart).

Read more about symptoms of pheochromocytoma on our adrenal surgery blog

How Is a Pheochromocytoma Treated?

Surgery to remove the tumor (adrenalectomy) is the treatment for almost all pheochromocytomas. Before the operation, most patients are prepared with blood-pressure medication (alpha-blockers such as doxazosin or phenoxybenzamine, sometimes other medicines) and good hydration; the plan is individualized by the team. Silent pheochromocytomas, with normal blood pressure, still need careful management around surgery. For people with hereditary or bilateral tumors, adrenal-sparing surgery (partial adrenalectomy) can often preserve enough healthy adrenal tissue to avoid lifelong steroid replacement. After surgery, everyone needs lifelong follow-up with a yearly metanephrine test.

Last updated October 2026.

---