Pituitary tumors, frequently called pituitary adenomas are relatively common primary brain tumors. These brain tumors represent 10-15% of primary brain tumors in adults. The majority of pituitary tumors are benign. There are, however, rare occurrences of pituitary carcinomas, and the pituitary gland can be a site of metastases from tumors outside of the nervous system. The term pituitary microadenoma refers to tumors smaller than one centimeter in greatest diameter.
SYMPTOMS
Pituitary tumors present in a number of different ways. The first relates to the production of hormones by the pituitary brain tumors. These pituitary brain tumors tend to be discovered when they are small. The symptoms produced are related to the type of hormone generated by the pituitary brain tumors. The more common pituitary brain tumors generate prolactin, which causes, in women, loss of the normal menstrual cycle and production of breast secretions. These pituitary brain tumors are called prolactinomas. Another hormone secreting pituitary brain tumors is the ACTH (a tumor that causes steroid production) secreting tumor. This is called Cushing’s disease. A third hormone secreting pituitary brain tumors causes excessive production of growth hormone. This is called acromegaly. Rare pituitary brain tumors can cause excess thyroid hormone. There are specific symptoms that relate to each of these tumors.
The second manner of presentation relates to increasing size of the pituitary brain tumors. These are usually pituitary brain tumors that do not cause hormone secretion. These pituitary brain tumors can get to be rather large and cause visual problems. The most common is the loss of peripheral vision. This can progress to blindness if not treated. Large pituitary brain tumors can also cause blockage of spinal fluid, which can result in hydrocephalus. Additionally, large pituitary brain tumors can compress the normal pituitary gland and cause a lack of hormones. Finally, there is something called pituitary apoplexy. This is a sudden onset of headache, visual loss, double vision and sometimes drowsiness that is caused by infarction or hemorrhage of the tumor. This last problem can become an emergency depending on its severity.
DIAGNOSIS
As always, the first steps in diagnosis are a careful history and physical examination. Consultation with an ophthalmologist and an endocrinologist are important in the diagnosis of pituitary tumors. MRI scanning performed without and with intravenous contrast enhancement is far better than CT scanning in the diagnosis of pituitary tumors.
TREATMENT
In the case of prolactin secreting pituitary brain tumors, particularly if the prolactin is very high, treatment with a medication called bromocriptine might be the recommendation. Surgery is also a common treatment for these pituitary brain tumors. There are two main ways of performing surgery on pituitary tumors. One is the so called transnasal, transsphenoidal approach. This is particularly good for smaller pituitary brain tumors, although many large pituitary brain tumors can be removed using this approach.
This type of surgery is often performed using an endoscope to assist with the surgery. The second approach to a pituitary brain tumors is to perform a craniotomy in the frontal part of the head, gently lifting the brain to approach the tumor. The particular approach depends on a number of factors including symptoms, size and location of the pituitary brain tumors and the medical condition of the patient.
Radiation therapy or stereotactic radiosurgery can also be used in the treatment of pituitary tumors both as additional treatment and as primary treatment. Sometimes after surgery or radiation, it may be necessary to take replacement hormones.