Adenoma (Encyclopedia of Cancer)
A benign (noncancerous) tumor that forms from the cells lining the inside or the surface of an organ.
Adenomas arise from cells that are specialized for secretion. These cells, called epithelial cells, are found throughout the body, but only a fraction is designed for secretion. This type of epithelial cell makes up specific organs and structures in the body known as glands. Glands produce sweat, saliva, mucus, milk, digestive juices, hormones, and an array of other substances. Hormone-secreting (endocrine) glands include the thyroid, pituitary, parathyroids, adrenals, and the ovaries and testes. Gland cells that secrete material outward through a duct, such as sweat glands and glands secreting digestive juices into the stomach and intestines, are called exocrine glands. Adenomas can arise from most of the gland cells in the body.
Adenomas result from excessive growth of normal epithelial cells. They arise in much the same way as malignant (cancerous) tumors but do not spread (metastasize) to nearby tissue or other parts of the body. New cells are normally created only when they are needed by the body. When the body does not need new cells and cell division continues, a mass or tumor is...
(The entire section is 1343 words.)
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