When patients hear the word "tumor," it usually causes some apprehension. While "tumor" is a term used to describe any abnormal growth of cells that forms a mass in the body, not all tumors are cancerous.

Tumors can grow from any cell in the body and, depending on the type of cell, they may either be benign or noncancerous, precancerous or cancerous, which are malignant tumors.

Many benign tumors are called adenomas, from the Greek aden, meaning "gland" and oma denoting the tumor or abnormal growth. Some tumors are visible if they are just under the skin like lipomas which are benign tumors made up of fatty tissue or in the front of the neck like a goiter which can be a thyroid adenoma.

But some tumors are only found by accident when tests are done to look at something else. Since the tumor is an unexpected finding and not related to why the test was done in the first place, it is called an incidental tumor or an "incidentaloma."

One of the more common incidentalomas is the adrenal incidentaloma. There are two adrenal glands, one found on top of each kidney, thus they are sometimes called the suprarenal glands. The adrenals are endocrine organs that produce hormones, such as cortisol, adrenaline and aldosterone, that control many functions in the body.

An adrenal tumor is considered an adrenal incidentaloma when it measures more than one centimeter and is found only by chance when a CT scan or MRI is done to examine the abdominal area for another reason. About one to 10 percent of patients who get these tests done have an adrenal incidentaloma, and it becomes more common with age.