What is pituitary adenoma?
Pituitary adenomas are common benign tumors of the pituitary gland. It is said that up to 10% of people will have a pituitary adenoma (which might never have caused a problem) by the time of their death. Some tumors secrete one or more hormones in excess. Such so-called secretory pituitary adenomas are usually found due to hormonal imbalances that affect bodily functions. They may be relatively small when detected.
There are multiple types of adenomas, classified by size and whether they produce hormones:
- Secreting tumors, functioning tumors, or endocrine-active tumors; About 50% of adenomas produce too much of one of the hormones.
- Non-functioning or endocrine-inactive pituitary tumor; Non-secreting pituitary tumors do not make extra hormones.
Symptoms related to overproduction of hormones:
- Prolactin-secreting pituitary adenoma (prolactinoma). The pituitary tumor causes and overproduction of prolactin, causing loss of menstrual periods and breast milk production in women. In men, high prolactin levels can lower testosterone levels, leading to diminished sexual interest.
- Growth hormone-secreting pituitary adenoma. An excessive production of growth hormone (GH) causes acromegaly in adults or gigantism in children. Symptoms include enlarged hands and feet and other changes in the body.
- ACTH-secreting pituitary adenoma. Excessive ACTH hormone production causes Cushing’s disease. Symptoms include unexpected weight gain, easy bruising of the skin and muscle weakness.
- TSH-secreting pituitary adenoma (thyrotropinoma). Excessive TSH hormone production leads to hyperthyroidism. These tumors are very rare.
Symptoms related to effect of a large pituitary adenoma (macroadenoma):
- Vision loss. This occurs when macroadenomas grow upward into the brain cavity, compressing the optic chiasm.
- A loss of the outer peripheral vision, called a bitemporal hemianopsia.
- Other visual problems: Loss of visual acuity (blurry vision), colors not perceived as bright as usual.
- Loss of pituitary function.
Four types of treatment may be considered for pituitary adenoma:
Many pituitary tumors can be removed by surgery using one of the following operations:
- Transsphenoidal surgery: A type of surgery in which the instruments are inserted into part of the brain by going through an incision (cut) made under the upper lip or at the bottom of the nose between the nostrils and then through the sphenoid bone (a butterfly-shaped bone at the base of the skull) to reach the pituitary gland.
- Endoscopic transsphenoidal surgery: A type of surgery in which an endoscope is inserted through an incision (cut) made at the back of the inside of the nose and then through the sphenoid bone to reach the pituitary gland. An endoscope is a thin, tube-like instrument with a light, a lens for viewing, and a tool for removing tumor tissue.
- Craniotomy: Surgery to remove the tumor through an opening made in the skull.
Even if the doctor removes all the cancer that can be seen at the time of the surgery, some patients may be given chemotherapy or radiation therapy after surgery to kill any cancer cells that are left.
Radiation therapy may be used to shrink the tumor, either in combination with surgery or for people who cannot have surgery.
Drugs may be given to stop a functioning pituitary tumor from making too many hormones.
Chemotherapy may be used as palliative treatment for pituitary carcinomas, to relieve symptoms and improve the patient’s quality of life. Chemotherapy uses drugs to stop the growth of cancer cells, either by killing the cells or by stopping them from dividing.
Non-Functioning Pituitary Tumor
About half of all pituitary tumors are what is called non-functioning tumors. This means that they do not produce any hormones themselves. But the presence and position of the tumor can cause headaches, vision problems or put pressure on the pituitary gland, causing it to stop producing the needed amount of one or more hormones. This leads to hypopituitarism.
The specific symptoms of a non-functioning pituitary tumor will depend on its location and its impact on surrounding tissues such as the pituitary gland, the optic nerves or the hypothalamus.
Some of the symptoms that might occur include:
- Diabetes insipidus
- Disturbed vision
- Dry skin
- Impotence for men
- Loss of (or irregular) monthly periods for women
- Loss of sex drive
- Low blood pressure and dizziness on standing (postural hypotension)
- Low energy
- Muscle weakness
- Pale skin
- Reduced fertility
- Sensitivity to cold
- Weight gain
Each of the symptoms described above occur in response to the loss of one or more of the hormones produced by the pituitary. Decrease in the production of only one hormone would not lead to all the symptoms described above.