Adenoma
Encyclopedia
An adenoma is a benign
tumor (-oma) of glandular origin. Adenomas can grow from many organs including the colon
, adrenal glands, pituitary gland
, thyroid
, prostate
, etc. Although these growths are benign
, over time they may progress to become malignant, at which point they are called adenocarcinoma
s. 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
).
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 (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.
. They are removed because of their tendency to become malignant and to lead to colon cancer.
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
.
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.
, is seen more often in women, and is frequently diagnosed during pregnancy as the hormone progesterone
increases its growth. Medical therapy with cabergoline
or bromocriptine
generally suppresses prolactinomas; progesterone antagonist therapy has not proven to be successful.
may secrete inappropriately high amounts of parathyroid hormone
and thereby cause primary hyperparathyroidism
.
. Hepatic adenomas are a rare benign tumour of the liver, which may present with hepatomegaly or other symptoms.
s. They are often very small and difficult to detect. Often there are no symptoms. Treatments can include a needle biopsy, and/or removal.
. They may cause carcinoid syndrome
, a type of paraneoplastic syndrome
.
is a cutaneous condition characterized by a slow-growing tumour usually presenting as a pink, flesh-coloured, or yellow papule or nodule.
Benign
A benign tumor is a tumor that lacks the ability to metastasize. Common examples of benign tumors include moles and uterine fibroids.The term "benign" implies a mild and nonprogressive disease. Indeed, many kinds of benign tumors are harmless to human health...
tumor (-oma) of glandular origin. Adenomas can grow from many organs including the colon
Colon (anatomy)
The colon is the last part of the digestive system in most vertebrates; it extracts water and salt from solid wastes before they are eliminated from the body, and is the site in which flora-aided fermentation of unabsorbed material occurs. Unlike the small intestine, the colon does not play a...
, adrenal glands, pituitary gland
Pituitary gland
In vertebrate anatomy the pituitary gland, or hypophysis, is an endocrine gland about the size of a pea and weighing 0.5 g , in humans. It is a protrusion off the bottom of the hypothalamus at the base of the brain, and rests in a small, bony cavity covered by a dural fold...
, thyroid
Thyroid
The thyroid gland or simply, the thyroid , in vertebrate anatomy, is one of the largest endocrine glands. The thyroid gland is found in the neck, below the thyroid cartilage...
, prostate
Prostate
The prostate is a compound tubuloalveolar exocrine gland of the male reproductive system in most mammals....
, etc. Although these growths are benign
Benign
A benign tumor is a tumor that lacks the ability to metastasize. Common examples of benign tumors include moles and uterine fibroids.The term "benign" implies a mild and nonprogressive disease. Indeed, many kinds of benign tumors are harmless to human health...
, over time they may progress to become malignant, at which point they are called adenocarcinoma
Adenocarcinoma
Adenocarcinoma is a cancer of an epithelium that originates in glandular tissue. Epithelial tissue includes, but is not limited to, the surface layer of skin, glands and a variety of other tissue that lines the cavities and organs of the body. Epithelium can be derived embryologically from...
s. Even while benign, they have the potential to cause serious health complications by compressing other structures (mass effect
Mass effect (medicine)
In medicine, a mass effect is the effect of a growing mass , for example the consequences of a growing cancer....
) and by producing large amounts of hormones in an unregulated, non-feedback-dependent manner (paraneoplastic syndrome
Paraneoplastic syndrome
A paraneoplastic syndrome is a disease or symptom that is the consequence of the presence of cancer in the body, but is not due to the local presence of cancer cells. These phenomena are mediated by humoral factors excreted by tumor cells or by an immune response against the tumor...
).
Histopathology
Adenoma is a benign tumor of epithelial tissue, such as the mucosa of stomach, small intestine, and colon, in which tumor cells form glands or glandlike structures.In hollow organs (digestive tract), the adenoma grows into the lumen - adenomatous polyp
Polyp (medicine)
A polyp is an abnormal growth of tissue projecting from a mucous membrane. If it is attached to the surface by a narrow elongated stalk, it is said to be pedunculated. If no stalk is present, it is said to be sessile. Polyps are commonly found in the colon, stomach, nose, sinus, urinary bladder...
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 (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.
Colon
Adenomas of the colon are quite prevalent. They are found commonly at colonoscopyColonoscopy
Colonoscopy is the endoscopic examination of the large bowel and the distal part of the small bowel with a CCD camera or a fiber optic camera on a flexible tube passed through the anus. It may provide a visual diagnosis and grants the opportunity for biopsy or removal of suspected...
. 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 is 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
Cortisol
Cortisol is a steroid hormone, more specifically a glucocorticoid, produced by the adrenal gland. It is released in response to stress and a low level of blood glucocorticoids. Its primary functions are to increase blood sugar through gluconeogenesis; suppress the immune system; and aid in fat,...
, causing Cushing's syndrome, aldosterone
Aldosterone
Aldosterone is a hormone that increases the reabsorption of sodium ions and water and the release of potassium in the collecting ducts and distal convoluted tubule of the kidneys' functional unit, the nephron. This increases blood volume and, therefore, increases blood pressure. Drugs that...
causing Conn's syndrome, or androgens causing hyperandrogenism
Hyperandrogenism
Hyperandrogenism is a medical condition characterized by excessive production and/or secretion of androgens.It is one of the primary symptoms of polycystic ovary syndrome. In such cases, it presents with symptoms such as acne or hyperseborrhea, is frequent in adolescent girls and is often...
.
Thyroid
About one in 10 people are found to have solitary thyroidThyroid
The thyroid gland or simply, the thyroid , in vertebrate anatomy, is one of the largest endocrine glands. The thyroid gland is found in the neck, below the thyroid cartilage...
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 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, prolactinomaProlactinoma
A prolactinoma is a benign tumor of the pituitary gland that produces a hormone called prolactin. It is the most common type of pituitary tumor...
, is seen more often in women, and is frequently diagnosed during pregnancy as the hormone progesterone
Progesterone
Progesterone also known as P4 is a C-21 steroid hormone involved in the female menstrual cycle, pregnancy and embryogenesis of humans and other species...
increases its growth. Medical therapy with cabergoline
Cabergoline
Cabergoline , an ergot derivative, is a potent dopamine receptor agonist on D2 receptors. In vitro, rat studies show cabergoline has a direct inhibitory effect on pituitary lactotroph cells...
or bromocriptine
Bromocriptine
Bromocriptine , an ergoline derivative, is a dopamine agonist that is used in the treatment of pituitary tumors, Parkinson's disease , hyperprolactinaemia, neuroleptic malignant syndrome, and type 2 diabetes.- Indications :Amenorrhea, female infertility, galactorrhea, hypogonadism, and acromegaly...
generally suppresses prolactinomas; progesterone antagonist therapy has not proven to be successful.
Parathyroid
An adenoma of a parathyroid glandParathyroid gland
The parathyroid glands are small endocrine glands in the neck that produce parathyroid hormone. Humans usually have four parathyroid glands, which are usually located on the rear surface of the thyroid gland, or, in rare cases, within the thyroid gland itself or in the chest...
may secrete inappropriately high amounts of parathyroid hormone
Parathyroid hormone
Parathyroid hormone , parathormone or parathyrin, is secreted by the chief cells of the parathyroid glands as a polypeptide containing 84 amino acids...
and thereby cause primary hyperparathyroidism
Primary hyperparathyroidism
Primary hyperparathyroidism causes hypercalcemia through the excessive secretion of parathyroid hormone , usually by an adenoma of the parathyroid glands.-Epidemiology:...
.
Liver
See Hepatocellular adenomaHepatocellular adenoma
Hepatocellular adenoma, also hepatic adenoma, or rarely hepadenoma, is an uncommon benign liver tumor which is associated with the use of hormonal contraception with a high estrogen content...
. Hepatic adenomas are a rare benign tumour of the liver, which may present with hepatomegaly or other symptoms.
Breast
Breast adenomas are called fibroadenomaFibroadenoma
Fibroadenomas of the breast, are lumps composed of fibrous and glandular tissue. Because breast cancer can also appear as a lump, doctors may recommend a tissue sample to rule out cancer in older patients...
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, 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 bronchiBronchus
A bronchus is a passage of airway in the respiratory tract that conducts air into the lungs. The bronchus branches into smaller tubes, which in turn become bronchioles....
. They may cause carcinoid syndrome
Carcinoid syndrome
Carcinoid syndrome refers to the array of symptoms that occur secondary to carcinoid tumors. The syndrome includes flushing and diarrhea, and, less frequently, heart failure and bronchoconstriction...
, a type of paraneoplastic syndrome
Paraneoplastic syndrome
A paraneoplastic syndrome is a disease or symptom that is the consequence of the presence of cancer in the body, but is not due to the local presence of cancer cells. These phenomena are mediated by humoral factors excreted by tumor cells or by an immune response against the tumor...
.
Sebaceous
A sebaceous adenomaSebaceous adenoma
Sebaceous adenoma is a cutaneous condition characterized by a slow-growing tumour usually presenting as a pink, flesh-coloured, or yellow papule or nodule.-Significance:...
is a cutaneous condition characterized by a slow-growing tumour usually presenting as a pink, flesh-coloured, or yellow papule or nodule.
External links
- Adrenal adenoma description at
- Photos (colon adenoma) at Atlas of Pathology