A pheochromocytoma (fee-o-kroe-moe-sy-TOE-muh) is a rare tumor that grows in an adrenal gland. Most often, the tumor is not cancer and has not spread to other parts of the body. This is called benign or nonmetastatic pheochromocytoma. Rarely, the tumor is cancer and has spread to other parts of the body. This is called malignant or metastatic pheochromocytoma.
You have two adrenal glands — one at the top of each kidney. The adrenal glands make hormones that help control key processes in the body, such as blood pressure. Usually, a pheochromocytoma forms in only one adrenal gland. But tumors can grow in both adrenal glands.
With a pheochromocytoma, the tumor releases hormones that can cause various symptoms. They include high blood pressure, headache, sweating and symptoms of a panic attack. If a pheochromocytoma isn't treated, serious or life-threatening damage to other body systems can happen.
Surgery to remove a pheochromocytoma often returns blood pressure to a healthy range.

A pheochromocytoma can cause large changes in blood pressure. When that happens, it's called a spell. Blood pressure may return to a healthy range between spells. That can make it harder to diagnose a pheochromocytoma. The graph shows a nine-day period of short, irregular bursts in blood pressure due to a pheochromocytoma. The lower points show the bottom number of the reading, called diastolic pressure. The higher points show the top number of the reading, called systolic pressure. For example, the first burst in blood pressure is seen on day two with a reading of 250/110 millimeters of mercury.
A pheochromocytoma often causes the following symptoms:
Some people with pheochromocytomas also have symptoms such as:
Some people with pheochromocytomas have no symptoms. They don't realize they have the tumor until an imaging test happens to find it.
Most often, the symptoms of pheochromocytoma come and go. When they start suddenly and keep coming back, they're known as spells or attacks. These spells may or may not have a trigger that can be found.
Certain activities or conditions can lead to a spell, such as:
Foods high in tyramine, a substance that affects blood pressure, also can trigger spells. Tyramine is common in foods that are fermented, aged, pickled, cured, overripe or spoiled. These foods include:
Certain medicines and drugs that can trigger spells include:
High blood pressure is one of the main symptoms of a pheochromocytoma. But most people who have high blood pressure don't have an adrenal tumor. Talk to your healthcare professional if any of these factors apply to you:
Researchers don't know exactly what causes a pheochromocytoma. The tumor forms in cells called chromaffin cells. These cells are located in the center of an adrenal gland. They release certain hormones, mainly adrenaline and noradrenaline. These hormones help control many body functions, such as heart rate, blood pressure and blood sugar.
Adrenaline and noradrenaline trigger the body's fight-or-flight response. That response happens when the body thinks there is a threat. The hormones cause blood pressure to rise and the heart to beat faster. They also prepare other body systems so you can react quickly. A pheochromocytoma causes more of these hormones to be released. And it causes them to be released when you're not in a threatening situation.
Most of the chromaffin cells are in the adrenal glands. But small clusters of these cells also are in the heart, head, neck, bladder, stomach area and along the spine. Chromaffin cell tumors located outside of the adrenal glands are called paragangliomas. They may cause the same effects on the body as a pheochromocytoma.

The endocrine system is made up of glands and organs that make hormones. The endocrine system includes the pituitary gland, thyroid gland, parathyroid glands, adrenal glands, pancreas, ovaries and testicles.
A person's age and certain medical conditions can raise the risk of a pheochromocytoma.
Most pheochromocytomas are found in people between the ages of 20 and 50. But the tumor can form at any age.
People who have certain rare genetic conditions have a higher risk of pheochromocytomas. The tumors usually are not cancer and haven’t spread in the body. This type of tumor is called benign or nonmetastatic pheochromocytoma. Rarely, the tumors are cancer and are spreading in the body. This type of tumor is called malignant or metastatic pheochromocytoma. Often, benign tumors related to these rare genetic conditions form in both adrenal glands. Genetic conditions linked with pheochromocytoma include:

People with MEN 2B have tumors on nerves in the lips, mouth, eyes and digestive tract. They also may have a tumor on the adrenal gland, called pheochromocytoma, and medullary thyroid cancer.
A pheochromocytoma can lead to other health problems. The high blood pressure linked with a pheochromocytoma can damage organs, especially tissues of the heart and blood vessel system, brain and kidneys. This damage can cause dangerous conditions, including:
Rarely, a pheochromocytoma spreads to other parts of the body. This tumor is then considered cancerous, also called malignant, and is referred to as metastatic pheochromocytoma. Cancer cells from a pheochromocytoma or paraganglioma most often travel to the lymph system, bones, liver or lungs.