n., pl., -mas, or -ma·ta (-mə-tə).
A benign epithelial tumor having a glandular origin and structure.
adenomatoid ad'e·nom'a·toid' (ăd'n-ŏm'ə-toid') adj.
adenomatous ad'e·nom'a·tous (-ŏm'ə-təs) adj.
adenoma
Dictionary:
ad·e·no·ma (ăd'n-ō'mə)  |
| 5min Related Video: adenoma |
| Oncology Encyclopedia: Adenoma |
Key Terms: Adrenal glands, Carcinoma, Colon, Epithelium, Parathyroid glands, Pituitary gland.
Definition
A benign (noncancerous) tumor that forms from the cells lining the inside or the surface of an organ.
Description
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 formed.
Tumors found on some glands are more likely to be adenomas than malignant tumors (carcinomas), including adrenal tumors, pituitary tumors, and salivary gland tumors. The adrenal tumor known as pheochromocytoma is benign in 90% of reported cases. The gastrinomas associated with Zollinger-Ellison syndrome are benign in 50% of patients with this condition. Adenomas are also associated with Cushing's syndrome, a disorder caused by excess levels of a hormone secreted by the adrenal glands. Although most cases are caused by a dysfunctional pituitary gland, 20–25% are due to adrenal adenomas.
The occurrence of an adenoma rarely indicates an increased chance for the later development of a carcinoma. However, colon cancer and rectal cancer are thought to arise from adenomas, and one type of lung adenoma—called a bronchial adenoma—can potentially develop into lung cancer.
Most adenomas affect the normal functioning of the organ or gland in which it arises, although some have no effect. Many secrete hormones, leading to elevated hormone levels in the blood and causing uncomfortable and sometimes life-threatening conditions.
Demographics
Certain types of adenomas are more common in women than in men (e.g., pituitary tumors and liver adenoma), and some are more common in older adults (e.g., adenomas of the colon). But specific demographics depend on the specific type of adenoma.
Causes and Symptoms
The cause of adenomas is often unknown. Liver adenomas in women are linked to the use of oral contraceptives, and some conditions, such as pheochromocytomas and colon adenomas, can be inherited.
No single set of symptoms can be applied to all adenomas. Some disorders have similar or identical symptoms whether due to an adenoma or carcinoma. Ultimately, the signs and symptoms depend on the location of the adenoma:
- Adrenal glands: an adrenocortical adenoma often shows the same symptoms of an adrenocortical carcinoma, including abdominal pain and loss of weight. A benign and malignant pheochromocytoma also has the same symptoms, including headaches, sweating, and chest pains.
- Breast: a marble-like benign fibroadenoma causes no symptoms and is either too small to detect by touch or is several inches across and easily detected.
- Colon or rectum: persistent diarrhea can indicate villous adenomas of the rectum. Blood in stool samples can indicate adenomas in the colon or rectum.
- Liver: a hepatic adenoma causes pain and a mass that is detectable by touch.
- Lung: a chronic or bloody cough, fever, chills, and shortness of breath can indicate a bronchial adenoma.
- Pancreas: pain in the abdomen, diarrhea, stomach pain, persistent fatigue, fainting, and weight gain can indicate one of the various types of pancreatic adenomas or pancreatic cancer.
- Parathyroid: weakness, fatigue, constipation, kidney stones, loss of appetite, and bone pain are signs of a condition known as hyperparathyroidism, which occurs in patients with parathyroid adenomas or parathyroid cancer.
- Salivary gland: adenomas are small and usually painless but can cause swelling around the chin or jawbone, numbness of the face, and pain in the face, chin, or neck.
- Stomach and intestine: a gastrinoma causes a peptic ulcer in the intestines or stomach. The occurrence of many ulcers in the stomach, intestine, and pancreas that do not respond well to treatment can indicate Zollinger-Ellison syndrome.
- Sweat gland: adenomas may appear as many small, smooth, and firm bumps on the lower eyelids and upper parts of the cheek (syringomas), or as small bumps with bluish or dark-brown coloration on the head and neck area (hidrocystoma). Solitary adenomas (poromas) occur on the sole of the foot or palm of the hand.
- Thyroid: a lump in the neck region accompanied by a cough and difficulty swallowing or breathing often indicates a benign thyroid nodule; however, these are the same symptoms for thyroid cancer.
Diagnosis
A variety of techniques is used to diagnose adenomas. Blood and urine samples are taken to detect elevated levels of hormones or other substances associated with a specific adenoma. Tumors are located using a combination of ultrasonography, computed tomography scan (CT scan), magnetic resonance imaging (MRI), and possibly radionuclide imaging. A biopsy is performed to determine whether a tumor is benign or malignant.
Treatment Team
A doctor who interprets tissue samples (a pathologist) and a doctor trained in examining x rays and computer images (a radiologist) will make an initial diagnosis. Adenomas are often surgically removed, so a surgical team consisting of an anesthesiologist, surgeon, and nurses is often associated with treatment.
Clinical Staging, Treatments, and Prognosis
Surgical removal is the recommended treatment for most adenomas, although the symptoms of some adenomas, such as pituitary tumors, can be treated with medication. In most cases, treatment cures the condition.
Questions to Ask the Doctor
- Does the occurrence of this adenoma increase my chances of developing cancer?
- If I choose to have the adenoma surgically removed, what are the chances that I will develop another adenoma?
- Will all my symptoms disappear once the adenoma is removed?
Clinical Trials
Two clinical trials completed in mid-2001 investigated treatments to prevent colon cancer in patients who have had surgery to remove adenomas of the rectum or colon. An 800 mg daily dose of folic acid may decrease the occurrence of colon cancer in patients who have had adenomas removed. The combined use of two drugs that are prescribed for other conditions, eflonithine and sulindac, may prevent the development of adenomas or the recurrence of colon cancer.
Resources
Books
DeVita, Vincent T. Jr., Samuel Hellman, and Steven A. Rosenberg, eds. Cancer: Principles and Practice of Oncology. Philadelphia: Lippincott-Raven Publishers, 1997.
Greenspan, Francis S., and Gordon J. Strewler. Basic and Clinical Endocrinology. Stamford, Connecticut: Appleton&Lange, 1997.
—Monica McGee, M.S.
| Dental Dictionary: adenoma |
(ad′ənō′mə)
n
n
A benign epithelial neoplasm or tumor with a basic glandular (acinar) structure, suggesting derivation from glandular tissue.
Adenoma. (Regezi/Sciubba/Jordan, 2003)
| Veterinary Dictionary: adenomatoid |
Resembling adenoma.
- congenital a. malformation — see bronchial hypoplasia.
| Wikipedia: Adenoma |
| Adenoma | |
|---|---|
| Classification and external resources | |
 Micrograph of a tubular adenoma (left of image), a type of colonic polyp and a precursor of colorectal cancer. Normal colorectal mucosa is seen on the right of the image. H&E stain. |
|
| ICD-10 | D12., D35.0, D34., D35.2, and others |
| ICD-9 | 211.3, 211.5,223.0, 226, 227.0, |
| ICD-O: | M8140/0 |
| MeSH | D000236 |
An adenoma is a benign tumor (-oma) of glandular origin. Adenomas can grow from many organs including the colon, adrenal glands, pituitary gland, thyroid, etc. Although these growths are benign, over time they may progress to become malignant, at which point they are called adenocarcinomas. Even while benign, they have the potential to cause serious health complications by compressing other structures (mass effect) and by producing large amounts of hormones in an unregulated, non-feedback-dependent manner (paraneoplastic syndrome).
Contents |
Histopathology
Adenoma (aldosteronoma) is a benign epithelial tumor arising in epithelium of mucosa (stomach, small intestine, and bowel), glands (endocrine and exocrine), and ducts. In hollow organs (digestive tract), the adenoma grows upwards into the lumen - adenomatous polyp or polypoid adenoma. Depending on the type of the insertion base, adenoma may be pedunculated lobular head with a long slender stalk, covered by normal mucosa or sessile (broad base).
The adenomatous proliferation is characterized by different degrees of cell dysplasia (atypia or loss of normal differentiation of epithelium) irregular cells with hyperchromatic nuclei, (pseudo)stratified nuclei, nucleolus, decreased mucosecretion, and mitosis. The architecture may be tubular, villous, or tubulo-villous. Basement membrane and muscularis mucosae are intact.
Locations
Colon
Adenomas of the colon are quite prevalent. They are found commonly at colonoscopy. They are removed because of their tendency to become malignant and to lead to colon cancer.
Renal
This is a tumor that is most often small and asymptomatic, and its derived from renal tubules. It may be a precursor lesion to renal carcinoma.
Adrenal
Adrenal adenomas are common, and are often found on the abdomen, usually not as the focus of investigation; they are usually incidental findings. About one in 10,000 is malignant. Thus, a biopsy is rarely called for, especially if the lesion is homogeneous and smaller than 3 centimeters. Follow-up images in three to six months can confirm the stability of the growth.
While some adrenal adenomas do not secrete hormones at all , often some secrete cortisol, causing Cushing's syndrome, aldosterone causing Conn's syndrome, or androgens causing hyperandrogenism.
Thyroid
About one in 10 people are found to have solitary thyroid nodules. Investigation is required because a small percentage of these are malignant. Biopsy usually confirms the growth to be an adenoma, but, sometimes, excision at surgery is required, especially when the cells found at biopsy are of the follicular type.
Pituitary
Pituitary adenomas are commonly seen in 10% of neurological patients. A lot of them remain undiagnosed. Treatment is usually surgical, to which patients generally respond well. The most common subtype, prolactinoma, is seen more often in women, and is frequently diagnosed during pregnancy as the hormone progesterone increases its growth. Medical therapy bromocriptine generally suppresses prolactinomas; progesterone antagonist therapy has not proven to be successful.
Liver
Hepatocellular adenoma, Hepatic adenomas are a rare benign tumour of the liver, which may present with hepatomegaly or other symptoms.
Breast
Breast adenomas are called fibroadenomas. They are often very small and difficult to detect. Often there are no symptoms. Treatments can include a needle biopsy, and/or removal.
Appendix
Adenomas can also appear in the appendix. The condition is extremely rare, and most physicians will never encounter an actual case, but they do happen. The most common version is called cystadenoma. They are usually discovered in the course of examination of the tissue following an appendectomy. If the appendix has ruptured and a tumor is present, this presents challenges, especially if malignant cells have formed and thus spread to the abdomen.
Bronchial
Bronchial adenomas are adenomas in the bronchi. They may cause carcinoid syndrome, a type of paraneoplastic syndrome.[1]
References
- ^ Table 6-5 in: Mitchell, Richard Sheppard; Kumar, Vinay; Abbas, Abul K.; Fausto, Nelson. Robbins Basic Pathology. Philadelphia: Saunders. ISBN 1-4160-2973-7. 8th edition.
External links
- Adrenal adenoma description at 00007 at CHORUS
- Photos (colon adenoma) at Atlas of Pathology
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