ON THIS PAGE: You will find some basic information about these diseases and the parts of the body they may affect. This is the first page of Cancer.Net’s Guide to Pheochromocytoma and Paraganglioma. Use the menu to see other pages. Think of that menu as a roadmap for this entire guide.

About endocrine and neuroendocrine tumors

A tumor begins when the DNA of healthy cells is damaged, causing the cells to change and grow with less control, forming a mass.

Pheochromocytomas and paragangliomas are considered a subset of a group of tumors called neuroendocrine tumors (NETs). A NET begins in the specialized cells of the body’s neuroendocrine system. These cells have traits of both hormone-producing endocrine cells and nerve cells. They are found throughout the body’s organs and help control many of the body’s functions. Hormones are chemical substances that are carried through the bloodstream to have a specific effect on the activity of other organs or cells in the body. All NETs have the potential to become metastatic, meaning the tumor can spread to other parts of the body. Most NETs take years to develop and grow slowly. However, some NETs can be fast-growing. See the Stages section of this guide to learn more.

It can be difficult to tell if a pheochromocytoma or paraganglioma will grow or spread, even after surgically removing the tumor and examining it under a microscope. The majority of these tumors will not spread.

About pheochromocytoma

A pheochromocytoma is a rare NET of the adrenal glands. The body has 2 of these small, yellowish glands. There is one on top of each kidney. Adrenal glands have 2 main parts that function separately: the outer adrenal cortex and the inner adrenal medulla. Each part produces a different set of hormones.

A pheochromocytoma begins in the chromaffin cells of the adrenal medulla. The cells release hormones called catecholamines during times of stress. Adrenaline and noradrenaline, which increase blood pressure and heart rate, are 2 of those catecholamines. A pheochromocytoma can cause uncontrolled surges of extra adrenaline and noradrenaline into the blood. Even though an estimated 90% of pheochromocytomas remain localized to the area they began, these hormone surges can still lead to life-threatening health problems, such as a stroke, heart attack, hemorrhage, or sudden death.

Most people develop a pheochromocytoma in 1 adrenal gland. Some people develop a tumor in both glands. There can also be multiple tumors in a gland. Pheochromocytomas usually grow slowly. Approximately 40% of pheochromocytomas occur because of an inherited genetic condition (see Risk Factors). Therefore, people with a pheochromocytoma should receive a genetic evaluation.

A pheochromocytoma is called a primary adrenal gland tumor because it starts inside an adrenal gland. Read about other types of primary adrenal gland tumors.

About paraganglioma

A paraganglioma is a rare NET that develops from the same type of cells that pheochromocytomas do (see above). However, paragangliomas form outside the adrenal glands. This type of tumor may also be called an extra-adrenal paraganglioma. The majority of paragangliomas form in the abdomen. They can also form in other parts of the body, including near the carotid artery, along nerve pathways in the head and neck, and in the chest, heart, and abdomen. Paragangliomas are less common than pheochromocytomas. Depending on the tumor's location in the body and certain genetic mutations, about 20% to 40% of paragangliomas can metastasize, or spread (see Diagnosis). Paragangliomas are typically slow growing. About 35% to 40% of paragangliomas occur because of an inherited genetic condition (see Risk Factors). Therefore, people with a pheochromocytoma should receive a genetic evaluation.

There are 2 types of paragangliomas:

• Functional (sympathetic) paragangliomas. Like pheochromocytomas, sympathetic paragangliomas almost always produce catecholamines. These tumors develop in the sympathetic nervous system, which controls the body’s response to stress and activity.

• Non-functional (parasympathetic) paragangliomas. These tumors are most often found in the head and neck. They usually do not release catecholamines, so they rarely cause hormone-related symptoms or signs of a problem. They develop in the parasympathetic nervous system, which controls the body during rest.

Looking for More of an Introduction?

If you would like more of an introduction, explore these related items. Please note that these links will take you to other sections on Cancer.Net:

• Find a Doctor. Search for a specialist in your local area using this free database of doctors from the American Society of Clinical Oncology (ASCO).

• Medical Terms. Learn what medical phrases and terms used in tumor care and treatment mean.

The next section in this guide is Statistics. It helps explain the number of people who are diagnosed with a pheochromocytoma or paraganglioma and general survival rates. Use the menu to choose a different section to read in this guide.