What are pituitary/hypophysis tumors
Excessive enlargement of cells in the pituitary gland (or hypophysis) causes it to have an irregular growth, which sets up a pituitary tumor, also called a hypophysis tumor.
This is considered the main gland in the human body. Located at the base of the brain, the pituitary has the function of regulating the work of other glands, such as the adrenal, thyroid, testes and ovaries. It also produces the hormones prolactin (essential for breastfeeding), oxytocin (important in labor), growth and secretes antidiuretic hormone, which helps control the amount of water in the body.
Pituitary tumors are usually noncancerous pituitary adenomas. However, although they are not cancerous, they can cause major health problems by secreting too much hormones or interrupting hormone production.
It is a rare disease, with tumors that are often small and never cause any symptoms. It can occur at any age, but is more common in older people.
The causes of the development of pituitary tumors are not known.
Subtypes of pituitary/hypophysis tumors
Pituitary adenomas are classified based on two parameters: size and hormone-producing capacity.
As for size, pituitary adenomas can be:
- Microadenomas – tumors less than 1 cm in diameter, which rarely compromise or damage the pituitary site where they are found or the tissues near the gland. They only cause symptoms if they release some hormone in excess, but many people with microadenomas never diagnose them or suffer any health consequences from them; and
- Macroadenomas – tumors larger than 1 cm in diameter, which can cause symptoms due to excessive production of a hormone and/or pressure on normal pituitary tissue or nearby nerves, such as the optic nerve.
As for the ability to produce hormones, pituitary adenomas can be:
- Functional – are pituitary adenomas that produce excess hormones, classified according to the hormone they produce (prolactin – 30% to 40%; growth hormone – 20%; other types, such as corticotropin, gonadotropin and thyrotropin). Some functional adenomas secrete more than one type of hormone; and
- Non-functional – also called null cell adenomas, these are pituitary adenomas that do not produce any type of hormone. They are responsible for about 30% of pituitary tumors.
Very rarely, pituitary tumors can be malignant, so they are called pituitary carcinomas. They can occur at any age, but are more common in older people, and they normally produce hormones.
Symptoms of pituitary/hypophysis tumors
The symptoms of pituitary tumors depend on the type of hormone produced in excess or not produced due to the disease. In common, the different types of tumors in this gland cause headaches, weakness, joint pain, loss or gain of appetite or weight for no apparent reason.
But they can cause specific symptoms, such as gigantism before puberty or acromegaly after puberty (when there is excessive production of growth hormone), diabetes insipidus (if there is less release of vasopressin as a result of compression of the hypothalamus), amenorrhea in women, and erectile dysfunction in men (excessive production of prolactin) and Cushing’s syndrome (excessive ACTH production).
The suspicion of pituitary tumor arises when the patient has unexplained headaches along with other symptoms, but in many cases these tumors are discovered by chance, in tests carried out because of another disease.
As benign adenomas often cause hormonal changes, specific blood and urine tests are performed to assess their levels. Then imaging tests, such as computed tomography and magnetic resonance imaging, are done to check if the tumor affects other nearby structures. In most of these cases, a biopsy of a small tissue sample from the affected region is the test that makes the diagnosis.
Pituitary carcinomas are very similar to adenomas in the area, so they are usually diagnosed when they have spread to other organs. This usually happens 5 to 10 years after the first surgery to treat the problem. The places where these malignant tumors tend to spread are the brain, spinal cord, meninges, or bone around the pituitary.
Pituitary tumors can be treated with medication, surgery, or both, depending on the case and the specialist’s assessment.
Pituitary tumors that secrete ACTH, growth hormone, or TSH are usually surgically removed; when they are inaccessible or multifocal, radiation therapy is necessary. Prolactin-producing adenomas, in turn, can be treated with drugs, making surgery and radiotherapy unnecessary.
After treatment, monitoring of hormone levels in the pituitary gland should be carried out; if they do not normalize, it is necessary to enter with medication.
Because pituitary tumors have no known cause, they cannot be prevented.