An adenoma is a benign tumor that has a glandular origin. Adenomas typically originate from cells used for secretion. Called epithelial cells, these cells are located throughout the body. However, only a portion of such cells is used for secretion. An adenoma forms when normal epithelial cells grow excessively.

Epithelial cells that are used for secretion make up specific parts of the body referred to as glands. Glands have the job of forming a number of substances in the body including, but not limited to, sweat, saliva, breast milk, mucous, and hormones. An adenoma can form from just about any glandular cell in the body.

An adenoma may form in a similar way to a malignant or cancerous tumor. A major difference between malignant tumors and adenomas is that adenomas do not metastasize or spread to other organs or tissues. Sometimes, however, adenomas develop into malignancies. When this happens, the newly malignant adenoma is called an adenocarcinoma.

Though it is possible for some adenomas to develop into cancerous tumors, having an adenoma is not usually predictive of the development of a malignancy. Most adenomas remain benign and do not form carcinomas. However, colon and rectal cancers may begin as adenomas. Additionally, bronchial adenomas can develop into lung cancer.

Frequently, adenomas have a noticeable affect on the organs or gland tissue in which they develop. Often, adenomas secrete hormones. When this occurs, the effects can be quite uncomfortable for the affected individual. In certain situations, the effects can even be deadly. However, some adenomas develop without any demonstrable effects.

There are certain types of adenomas that are more common in women, such as adenomas of the liver. Others, such as colon adenomas, are most common in adults of advancing age. The cause of adenomas is not yet known.

There are some things that seem to make developing adenomas more likely. For example, women who use oral contraceptives may be at increased risk of developing liver adenomas. Furthermore, certain types of adenomas may be inheritable. This is true of colon adenomas.

Symptoms related to adenomas vary widely. For example, a breast adenoma, called a fibroadenoma, typically causes no symptoms and may be so small that the affected individual is unable to detect it. Other breast adenomas, however, may be large enough to be noticeable by touch. By contrast, a lung adenoma can cause fever, chills, shortness of breath, and a bloody cough.

Adenomas are diagnosed using a variety of techniques, including the collection of blood and urine samples, ultrasound imaging, computed tomography (CT) scanning, and magnetic resonance imaging (MRI). Biopsies are typically employed to determine whether the tumor is benign or malignant. Treatment usually involves removal of the adenoma, although medication may be used to treat symptoms as well.