Benign (non-cancerous) tumors called adenomas are the most common type of pituitary tumor. Even though they are not cancerous, these tumors can cause health problems in several ways:
- By damaging the healthy pituitary gland
- By making too many pituitary hormones
- By pressing on nerves that control vision or other functions
A tumor can cause problems in all these ways, or just one or two.
About 40 percent of all pituitary adenomas (non-cancerous tumors) are non-functioning. This means they do not produce any hormones on their own.
About 10 percent of people have tiny pituitary tumors called microadenomas. These tumors are two or three millimeters in diameter, about the size of a peppercorn. Most people with microadenomas don't know they have them, and these tumors never cause symptoms. Doctors are not usually concerned about these very small tumors.
If a microadenoma grows, it can cause symptoms. A pituitary adenoma larger than one centimeter, about the size of a pencil eraser, is called a macroadenoma. As a macroadenoma grows larger, it can cause headaches, vision problems and other symptoms. Many macroadenomas are found by a doctor at this stage.
A pituitary adenoma can cause:
- Pituitary hormone deficiencies (not enough of one or more hormones made by the pituitary gland). As the pituitary adenoma grows, it can damage normal pituitary tissue. This can cause the pituitary gland to make fewer hormones than normal. The pituitary gland might be damaged permanently. If this happens, you might need to take extra hormones by mouth even after the adenoma is removed with surgery.
- Headaches when the tumor stretches the covering of the brain. Removing the tumor usually relieves the headaches. Pituitary tumors can also cause sudden, intense headaches when part of the tumor dies.
- Vision loss. The pituitary tumor presses on the area where nerve fibers carry information from your peripheral (side) vision. If the tumor is not treated, you could become blind, but vision problems usually go away if the tumor is removed.
- Cranial nerve disturbances.If the pituitary tumor presses on the cranial nerve, you may have problems aiming your eyes in the right direction.Note: A sudden, intense headache, often described as "the worst headache of my life" can be the presenting sign of pituitary apoplexy (the dying of the center of a large tumor due to it outgrowing its blood supply).
If you have a macroadenoma, a neurosurgeon (doctor specializing in the nervous system) can usually remove it. If your doctor is not able to remove the entire tumor, you might have radiation therapy to shrink tumor tissue or keep the tumor from growing.
Functioning adenomas are pituitary tumors that make too much of one or more hormones. Main types are:
- Adrenocorticotropic hormone (ACTH) secreting adenomas
- Growth hormone (GH) secreting adenomas
Other types of functional adenomas
- Thyroid stimulating hormone (TSH) secreting pituitary adenomas are very unusual but do occur.
- Interestingly, they are not always associated with hyperthyroidism because the TSH may be dysfunctional. Like non-functional adenomas, "TSH-omas" are treated surgically. Of note, some "non-functioning" adenomas actually secrete inactive hormones or hormone components but these compounds are generally considered to be clinically insignificant. They are also treated surgically if they are growing or are causing "mass effects" due to their size.
Other pituitary tumors – treated with surgery
Not all pituitary tumors are adenomas. Some other pituitary tumors need to be removed with surgery. These include:
Craniopharyngiomas are tumors that can damage the hypothalamus, a gland at the base of your brain. They often cause damage in children and young adults, but can occur in adults. These tumors develop from a structure that is present before birth. If the structure does not go away after birth, it can become a tumor.
Craniopharyngiomas can cause:
- Problems controlling body temperature
- Behavior problems
- Other problems
If you have a craniopharyngioma removed, you might also need radiation therapy.
Meningiomas are tumors that usually do not metastasize (spread to other areas of the body). They can be difficult to remove. During surgery, your doctor will remove as much of the tumor as possible without damaging other organs. If you have a meningioma removed, you might also need radiation therapy.
Cystic lesions (cysts) in the pituitary gland are tumors that contain fluid, tissue or other material. Some pituitary cyst types are:
- Rathke's cleft cysts
- Colloid cysts
- Arachnoid cysts
Pituitary cysts can cause headaches, vision problems and pituitary gland damage. If you have a pituitary cyst that causes symptoms, your doctor might do surgery to remove it.
Rare pituitary tumors
Rare pituitary gland tumors include some types of brain and spinal tumors. These can be:
- Metastatic tumors (spread from another area in the body)
- Germ cell tumors
- Epidermoid cysts
Treatment can include surgery, radiation therapy, chemotherapy or other medication. Your doctor will talk with you about the best treatment for a rare pituitary tumor.
Other pituitary conditions – treated with medication
Empty sella syndrome
Empty sella syndrome happens when part of the brain and spinal cord covering bulges into the pituitary gland area. This pushes the pituitary gland into your skull. It can cause damage to the gland, and affect hormone balance because the pituitary gland cannot produce hormones normally. Empty sella syndrome is treated with medication to replace the lost pituitary hormones.
Low pituitary hormone levels after radiation or surgery
If you had radiation treatment or surgery in the past, this might affect the pituitary gland's ability to make hormones. The condition can develop many years after you have treatment. It is treated with medication to replace the lost pituitary hormones.
Some diseases cause low pituitary hormone levels (hypopituitarism). Diseases that cause this include:
- Histiocytosis X
These diseases also affect other areas of the body. If you have one of these diseases, you need treatment with a specialist.
If you have a head injury, immune system disorder, infection or genetic (hereditary) condition, this can also cause low pituitary hormone levels. Your doctor treats you with medication to replace the lost pituitary hormones. You also receive treatment for the disease or condition causing low hormone levels.