“Adenoma” – you may have heard this word before, or not. There may be relatives who have had examinations investigating an adenoma. Adenomas are not uncommon. The Western world has the highest number of reported cases of adenomas. However, Asians and Africans also are also prone to specific types of adenomas. Although this condition is common, people usually have very little knowledge about it.
What is an adenoma?
An adenoma is a benign tumor which originates from or is related to a gland in our body. An adenoma may or may not have tissues similar to glands. There are adenomas that secrete certain hormones or enzymes and there are some which don’t. The name implies the location of the tumor. The “oma” suffix used in tumor nomenclature describes benign tumors.
What is a benign tumor?
A tumor is said to be benign when microscopic appearances are considered relatively innocent, meaning that it will remain localized, and not spread to adjacent tissues. It is possible to perform a local surgical procedure to remove a benign tumor. Most benign tumors are non-fatal, but in some rare instances clinicians have found that benign tumors could possibly cause death.
Adenomas are related to varies body tissues and are named after the organs or tissues they are related to. Let’s discuss several common adenomas.
The pituitary gland is situated in our brain just behind the eyes. It is composed of two parts which are called the anterior and posterior pituitary. The pituitary gland secretes hormones which control bodily functions. Pituitary adenoma is a slow-growing tumor normally located in the anterior pituitary gland. There are three main types, categorized according to size:
- Micro adenoma – size less than 10 mm
- Macro adenoma – size more than 10 mm
- Giant adenoma – size more than 40 mm
Pituitary adenomas can be functioning or non-functioning. Functioning adenomas are hormone secreting tumors which generally cause symptoms and signs related to excessive hormonal changes. Nonfunctioning adenomas don’t secrete hormones, but they can cause compression over the nearby structures and show symptoms and signs related to low hormonal levels in the body.
An exact cause for pituitary adenoma is unknown. Scientists think that genetic mutations are the most probable reason for this. Mutations can be found in certain genes like MEN1 and MEN4. The incidence of pituitary adenomas has not been properly investigated. Most pituitary adenomas are incidental findings that occur while investigating for other diseases (e.g., MRI of the head). Although they were autopsy related, meta analysis on this shows 10.5% of autopsies positive with pituitary adenomas. The study was not considered accurate because of the small sample size.
Because of the compressive effect of adenoma, there can be visual impairment due to pressure on the optic chiasma. Headache is the most common symptom as well as hormonal deficiency. The main hormones affected by pituitary adenoma are growth hormone, gonadotropin (which regulates sexual functions), thyroid stimulating hormone (TSH), and adrenal corticotropic hormone (ACTH).
Treatments for the condition depend on the size and functions of the adenoma. If it is a micro adenoma there’s less chance of needing surgery. Treating for hormonal imbalance is the primary treatment modality. If the size of the tumor is large and causing compressive effects, it is recommended to remove it with surgical procedure. Radiation therapy also plays a role in reducing the size of the tumor.
Approximately 10% of all gastric polyps are adenomas. There are proven relationships between familial adenomatous polyposis (FAP) gene mutations and gastric adenomas. This condition almost always occurs in the background of chronic gastritis. The incidence of gastric adenomas increases with age with the highest number of cases reported between the ages of 50 and 60 years. Men are three times more likely than females to get gastric adenomas.
The possibility of converting this benign tumor into a malignancy depends on the size of the tumor. If it is more than 2cm in size there is a high chance of it. An estimated 30% of reported malignant gastric tumors are adenomas.
Lactating adenomas are relatively less common palpable tumors. They can be found in late term pregnancy or in lactating women after their first pregnancy, and who are in their 20s or 30s. Although this condition is not dangerous it needs to be investigated. Three percent of all breast cancers occur during the pregnancy period of a woman’s life. The characteristic feature of a lactating adenoma is firm to the touch, painless on palpation, and mobile. It responds to hormonal changes in the body, therefore the size normally becomes regressed after lactation.
The adrenal gland is situated above the kidneys and has two parts called medulla and cortex. Both parts secrete different hormones. Adrenal adenomas are only confined to the cortex of the gland. These tumors can be functional or nonfunctional. Most of these tumors are found as incidental findings while investigating other ailments. Symptoms related to over-production of adrenal hormones are the presenting problems in most patients.
The cause of adrenal adenomas is identified as mainly genetic mutations. CTNNB1 gene mutation is the most common of them. A recent study shows that women are more affected with adrenal tumors than men.
The presenting symptoms due to adrenal adenoma vary with the affecting hormones. Cushing Syndrome occurs when your body is exposed to high levels of cortisol for long periods of time. Obesity, acne, purple straie on skin, menstrual irregularity, and muscle weakness can occur with excessive glucocorticoid production. High blood pressure and electrolyte changes in blood can occur with aldosterone hormone imbalance.
Hormone treatment and the surgical removal of the adrenal glands would be the treatment options if the symptoms are troublesome for the patient.
The parathyroid glands are located in the neck behind the thyroid gland. There are four parathyroid glands which regulate the calcium in our body. The size of a gland would be similar to an apple seed which weighs about 0.5g. The micro adenomas of the parathyroid gland are smaller in size (i.e., 0.1g) and giant adenomas may be up to 2g.
Parathyroid adenoma causes excessive secretion of parathyroid hormone. Parathyroid hormone regulates blood calcium and phosphate levels which are helpful in bone metabolism and muscle functions. Therefore, hyperparathyroidism causes high calcium and low phosphate levels in the blood, ultimately causing abdominal pain, renal stones, bone pain,and psychiatric problems.
The best method of treatment is surgical removal of the adenoma with the gland.
Adenomas in the colon are described in this category of villous adenomas. Normally adenomas occur within polyps in the colon. Polyps are finger-like or leaf-like projections in the colon, which are normal in most people. The incidence of polyps increase with age. Colonic adenomas are sorted into three main categories which are dependent on the percentage of villous features they have.
- Villous adenoma – contain more than 75% of villous features
- Tubular villous adenoma – contain 25% to 75% of villous features
- Tubular adenoma – contain less than 25% of villous features
Colonic adenomas are generally not symptomatic and can be easily detected in colonoscopy.
The causes for colonic adenomas are mainly genetic or environmental. Familial adenomatous polyposis (FAP) is directly related with the villous adenoma. It is also associated with the APC gene mutation in cells.
Colonic adenomas present with bowel obstructions, rectal bleeding, and altered bowel habits. Surgical removal of the affected region would be an option if the condition affects the patient severely.