A pheochromocytoma is a tumor which is usually found in the adrenal gland. It secretes hormones that are similar to, and often include, adrenaline. Adrenaline is also called epinephrine.
A pheochromocytoma tumor is usually found in the adrenal gland, although it may occur in other places. The body has two adrenal glands, which sit on top of the kidneys. The tumor often causes symptoms because of the adrenaline-like hormones it secretes. A pheochromocytoma tends to have sudden releases of hormones, which cause a sudden "attack", or onset of symptoms.
The cause of a pheochromocytoma is unknown. Some rare inherited conditions can increase the risk of getting this tumor. These conditions include the MEN syndrome, which is an inherited disease that causes tumors in many glands, and neurofibromatosis, a genetic disorder that affects the growth of nerve tissue.