Pheochromocytoma is a rare tumor of adrenal glands. It results in the release of too much epinephrine and norepinephrine hormones that control heart rate, metabolism, and blood pressure.

The illustration above shows human kidneys detailed image with a cross section of the adrenal gland. The adrenal glands are small glands that sit atop each kidney. They produce hormones that you can't live without, including sex hormones and cortisol. Cortisol helps you respond to stress among many other important functions. Some people are born that they are unable to make enough cortisol.

Adrenal cancer generally develops in the outermost layer of the adrenal glands. It develops as a tumor in most cases. A cancerous tumor of the adrenal gland is called an adrenal cortical carcinoma. A non-cancerous tumor of the adrenal gland is called a benign adenoma.

Photograph showing adrenal gland cells under the microscope. Adrenal medulla is the inner part of the gland and controls hormones that initiate the flight or fight response. The cells of the adrenal medulla secrete a class of hormones called catecholamines, adrenaline. Norepinephrine is also secreted from these cells.

The adrenal gland is located at the top of each kidney and is also known as suprarenal gland. Each adrenal gland has two parts: an inner medulla (produces epinephrine and norepinephrine (adrenaline and noradrenaline)) and an outer cortex (produces steroid hormones). Sometimes, adrenal glands produce too much aldosterone, which elevates the blood pressure. Uncontrolled high blood pressure therefore increases the risks for stroke, heart attack, heart failure, or kidney disorders. [Image is under public domain created by National Cancer Institute (Alan Hoofring)