About 5% of people who have a CT scan of the abdomen are found to have an adrenal tumor that was not suspected. Some of these adenomas are discovered by accident (incidentally) when CT or MRI scans of the abdomen are done because of an unrelated health problem. Most people with adrenal adenomas have no symptoms and don't know that they have an adrenal tumor. They usually occur in only one adrenal gland, but sometimes both. These tumors are usually less than 2 inches (5 centimeters) across. Most tumors of the adrenal cortex are benign tumors known as adenomas. Adenomas do not spread outside the adrenal gland. Sometimes the only way to know for sure that an adrenal tumor is a cancer is when it spreads to lymph nodes or other organs and tissues. These types of tumors can sometimes be hard to tell apart when the cells are looked at under the microscope. Carcinomas (malignant or cancerous tumors).Adenomas (benign or non-cancerous tumors).The 2 main types of adrenal cortex tumors are:

Neuroblastomas are covered separately elsewhere. Tumors and cancers of the adrenal cortex are covered here, but tumors of the adrenal medulla are not. Tumors and cancers that start in the adrenal medulla include pheochromocytomas (which are most often benign) and neuroblastomas. Nervous system hormones such as norepinephrine and epinephrine (also called adrenaline) are made in the medulla. The inner part of the adrenal gland, the medulla, is really an extension of the nervous system. The ovaries produce most of the estrogens (female hormones) in women. The testicles produce most of the androgens (male hormones) in men.

The amount of these hormones that result from conversion of adrenal androgens is small compared to what is made in other parts of the body.

Adrenal androgens can be converted to more common forms of the sex hormones estrogen and testosterone in other parts of the body.

Aldosterone helps the kidneys regulate the amount of salt in the blood and helps regulate blood pressure.

Cortisol causes changes in metabolism to help the body to handle stress.

These hormones all have a similar chemical structure and are called steroids: The cortex makes certain hormones for the body. The outer part, the cortex, is where most tumors develop.