An adenoma is a
benign tumor
A benign tumor is a mass of cells (tumor) that does not invade neighboring tissue or metastasize (spread throughout the body). Compared to malignant (cancerous) tumors, benign tumors generally have a slower growth rate. Benign tumors have re ...
of
epithelial
Epithelium or epithelial tissue is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. It is a thin, continuous, protective layer of compactly packed cells with a little intercell ...
tissue with
glandular origin, glandular characteristics, or both. Adenomas can grow from many glandular
organs, including the
adrenal glands
The adrenal glands (also known as suprarenal glands) are endocrine glands that produce a variety of hormones including adrenaline and the steroids aldosterone and cortisol. They are found above the kidneys. Each gland has an outer cortex whic ...
,
pituitary gland
In vertebrate anatomy, the pituitary gland, or hypophysis, is an endocrine gland, about the size of a chickpea and weighing, on average, in humans. It is a protrusion off the bottom of the hypothalamus at the base of the brain. The ...
,
thyroid
The thyroid, or thyroid gland, is an endocrine gland in vertebrates. In humans it is in the neck and consists of two connected lobes. The lower two thirds of the lobes are connected by a thin band of tissue called the thyroid isthmus. The thy ...
,
prostate
The prostate is both an accessory gland of the male reproductive system and a muscle-driven mechanical switch between urination and ejaculation. It is found only in some mammals. It differs between species anatomically, chemically, and phys ...
, and others. Some adenomas grow from epithelial tissue in nonglandular areas but express glandular tissue structure (as can happen in
familial polyposis coli
Gardner's syndrome (also known as Gardner syndrome, familial polyposis of the colon, or familial colorectal polyposis) is a subtype of familial adenomatous polyposis (FAP). Gardner syndrome is an autosomal dominant form of polyposis characterize ...
). Although adenomas are
benign
Malignancy () is the tendency of a medical condition to become progressively worse.
Malignancy is most familiar as a characterization of cancer. A ''malignant'' tumor contrasts with a non-cancerous ''benign'' tumor in that a malignancy is not s ...
, they should be treated as pre-cancerous. Over time adenomas may
transform
Transform may refer to:
Arts and entertainment
* Transform (scratch), a type of scratch used by turntablists
* ''Transform'' (Alva Noto album), 2001
* ''Transform'' (Howard Jones album) or the title song, 2019
* ''Transform'' (Powerman 5000 album ...
to become
malignant
Malignancy () is the tendency of a medical condition to become progressively worse.
Malignancy is most familiar as a characterization of cancer. A ''malignant'' tumor contrasts with a non-cancerous ''benign'' tumor in that a malignancy is not s ...
, at which point they are called
adenocarcinomas. Most adenomas do not transform. However, even though benign, they have the potential to cause serious health complications by compressing other structures (
mass effect
''Mass Effect'' is a military science fiction media franchise created by Casey Hudson, Drew Karpyshyn and Preston Watamaniuk. The franchise depicts a distant future where humanity and several alien civilizations have colonized the known unive ...
) and by producing large amounts of
hormones in an unregulated, non-feedback-dependent manner (causing
paraneoplastic syndromes). Some adenomas are too small to be seen macroscopically but can still cause clinical symptoms.
Histopathology
Adenoma is a benign tumor of glandular tissue, such as the mucosa of stomach, small intestine, and colon, in which tumor cells form glands or gland like structures.
In hollow organs (digestive tract), the adenoma grows 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) or sessile (broad base).
The adenomatous proliferation is characterized by different degrees of cell
dysplasia
Dysplasia is any of various types of abnormal growth or development of cells (microscopic scale) or organs ( macroscopic scale), and the abnormal histology or anatomical structure(s) resulting from such growth. Dysplasias on a mainly microscopi ...
(
atypia
Atypia (from Greek, ''a'' + ''typos'', without type; a condition of being irregular or nonstandard) is a histopathologic term for a structural abnormality in a cell, i.e. it is used to describe atypical cells.
Atypia can be caused by an infection ...
or loss of normal differentiation of epithelium) irregular cells with hyperchromatic nuclei, stratified or pseudostratified 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, also called
adenomatous polyps, 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.
Ashkenazi Jews have a 6% higher risk rate of getting adenomas, and then colon cancer, than do the general population, so it is important that they have regular actual colonoscopies, and specifically none of the less invasive diagnostic methods.
Renal
This is a tumor that is most often small and asymptomatic, and is derived from renal tubules. It may be a precursor lesion to
renal carcinoma
Renal cell carcinoma (RCC) is a kidney cancer that originates in the lining of the proximal convoluted tubule, a part of the very small tubes in the kidney that transport primary urine. RCC is the most common type of kidney cancer in adults, res ...
.
Adrenal
![Adrenal adenoma2 T1FS](https://upload.wikimedia.org/wikipedia/commons/3/39/Adrenal_adenoma2_T1FS.jpg)
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
Cushing's syndrome is a collection of signs and symptoms due to prolonged exposure to glucocorticoids such as cortisol. Signs and symptoms may include high blood pressure, abdominal obesity but with thin arms and legs, reddish stretch marks, a ...
,
aldosterone causing
Conn's syndrome
Primary aldosteronism (PA)'','' also known as primary hyperaldosteronism or Conn's syndrome, refers to the excess production of the hormone aldosterone from the adrenal glands, resulting in low renin levels and high blood pressure. This abnormalit ...
, or
androgens
An androgen (from Greek ''andr-'', the stem of the word meaning "man") is any natural or synthetic steroid hormone that regulates the development and maintenance of male characteristics in vertebrates by binding to androgen receptors. This in ...
causing
hyperandrogenism
Hyperandrogenism is a medical condition characterized by high levels of androgens. It is more common in women than men. Symptoms of hyperandrogenism may include acne, seborrhea (inflamed skin), hair loss on the scalp, increased body or facia ...
.
Thyroid
About one in 10 people is found to have solitary
thyroid
The thyroid, or thyroid gland, is an endocrine gland in vertebrates. In humans it is in the neck and consists of two connected lobes. The lower two thirds of the lobes are connected by a thin band of tissue called the thyroid isthmus. The thy ...
nodules. Investigation is required because a small percentage of these is 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 adenoma
Pituitary adenomas are tumors that occur in the pituitary gland. Most pituitary tumors are benign, approximately 35% are invasive and just 0.1% to 0.2% are carcinomas.[prolactinoma
A prolactinoma is a tumor ( adenoma) of the pituitary gland that produces the hormone prolactin. It is the most common type of functioning pituitary tumor. Symptoms of prolactinoma are due to abnormally high levels of prolactin in the blood (hyp ...]
, is seen more often in women, and is frequently diagnosed during pregnancy as the hormone
progesterone increases its growth. Medical therapy with
cabergoline
Cabergoline, sold under the brand name Dostinex among others, is a dopaminergic medication used in the treatment of high prolactin levels, prolactinomas, Parkinson's disease, and for other indications. It is taken by mouth.
Cabergoline is an e ...
or
bromocriptine
Bromocriptine, originally marketed as Parlodel and subsequently under many brand names, is an ergoline derivative and dopamine agonist that is used in the treatment of pituitary tumors, Parkinson's disease, hyperprolactinaemia, neuroleptic ...
generally suppresses prolactinomas; progesterone antagonist therapy has not proven to be successful.
Parathyroid
An adenoma of a
parathyroid gland
Parathyroid glands are small endocrine glands in the neck of humans and other tetrapods. Humans usually have four parathyroid glands, located on the back of the thyroid gland in variable locations. The parathyroid gland produces and secretes pa ...
may secrete inappropriately high amounts of
parathyroid hormone
Parathyroid hormone (PTH), also called parathormone or parathyrin, is a peptide hormone secreted by the parathyroid glands that regulates the serum calcium concentration through its effects on bone, kidney, and intestine.
PTH influences bone ...
and thereby cause
primary hyperparathyroidism
Primary hyperparathyroidism (or PHPT) is a medical condition where the parathyroid gland (or a benign tumor within it) produce excess amounts of parathyroid hormone (PTH). The symptoms of the condition relate to the resulting elevated serum calcium ...
.
Liver
Hepatic adenomas are a rare benign tumour of the liver, which may present with hepatomegaly or other symptoms.
Breast
Breast adenomas are called
fibroadenoma
Fibroadenomas are benign breast tumours characterized by an admixture of stromal and epithelial tissue. Breasts are made of lobules (milk producing glands) and ducts (tubes that carry the milk to the nipple). These are surrounded by glandula ...
s. 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. 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
A bronchus is a passage or airway in the lower respiratory tract that conducts air into the lungs. The first or primary bronchi pronounced (BRAN-KAI) to branch from the trachea at the carina are the right main bronchus and the left main bronchus. ...
. They may cause
carcinoid syndrome
Carcinoid syndrome is a paraneoplastic syndrome comprising the signs and symptoms that occur secondary to carcinoid tumors. The syndrome includes flushing and diarrhea, and less frequently, heart failure, vomiting and bronchoconstriction. It ...
, a type of
paraneoplastic syndrome.
Sebaceous
A
sebaceous adenoma is a
cutaneous
Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation.
Other animal coverings, such as the arthropod exoskeleton, have different d ...
condition characterized by a slow-growing tumour usually presenting as a pink, flesh-coloured, or yellow papule or nodule.
Salivary glands
Most salivary gland tumors are benign – that is, they are not cancer and will not spread to other parts of the body. These tumors are almost never life-threatening.
There are many types of benign salivary gland tumors, with names such as adenomas, oncocytomas, Warthin tumors, and benign mixed tumors (also known as pleomorphic adenomas).
Benign tumors are almost always cured by surgery. Very rarely, they may become cancer if left untreated for a long time or if they are not completely removed and grow back. It's not clear exactly how benign tumors become cancers. There are many types of salivary gland cancers. Normal salivary glands are made up of several different types of cells, and tumors can start in any of these cell types. Salivary gland cancers are named according to which of these cell types they most look like when seen under a microscope. The main types of cancers are described below.
Doctors usually give salivary cancers a grade (from 1 to 3, or from low to high), based on how abnormal the cancers look under a microscope. The grade gives a rough idea of how quickly it is likely to grow and spread.
* Grade 1 cancers (also called low grade or well differentiated) look very much like normal salivary gland cells. They tend to grow slowly and have a good outcome (prognosis).
* Grade 2 cancers (also called intermediate grade or moderately differentiated) have an appearance and outlook that is between grade 1 and grade 3 cancers.
* Grade 3 cancers (also called high grade or poorly differentiated) look very different from normal cells and often grow and/or spread quickly. The outlook for these cancers is usually not as good as for lower grade cancers.
Prostate
Prostate adenoma develops from the periurethral glands at the site of the median or lateral lobes.
Treatment
A physician's response to detecting an adenoma in a patient will vary according to the type and location of the adenoma among other factors. Different adenomas will grow at different rates, but typically physicians can anticipate the rates of growth because some types of common adenomas progress similarly in most patients. Two common responses are removing the adenoma with surgery and then monitoring the patient according to established guidelines.
One common example of treatment is the response recommended by
specialty professional organizations
A professional association (also called a professional body, professional organization, or professional society) usually seeks to further a particular profession, the interests of individuals and organisations engaged in that profession, and th ...
upon removing adenomatous polyps from a patient. In the common case of removing one or two of these polyps from the colon from a patient with no particular risk factors for cancer, thereafter the best practice is to resume surveillance colonoscopy after 5–10 years rather than repeating it more frequently than the standard recommendation.
References
External links
* Adrenal adenoma description at
* Photos (colon adenoma) a
Atlas of Pathology
{{ICDOMorphology
Anatomical pathology
Glandular and epithelial neoplasia