1. What causes a pituitary tumor to develop?
Pituitary tumors are common. In autopsy studies of patients who did not have known pituitary disease, as many as 26% had a small tumor (adenoma) in the gland. Molecular biology studies have shown that a change in the DNA of pituitary cells can cause unregulated growth of a particular cell type resulting in a pituitary tumor, called an adenoma. There are no known environmental causes. Very uncommonly, pituitary tumors may be inherited. In most of these patients, there is usually a family history of other endocrine (parathyroid or pancreas) tumors or of dark skin spots and skin and heart tumors), though in a few, there may be only pituitary tumors.
2. Is a pituitary tumor a brain tumor?
The pituitary gland is NOT in the brain and pituitary tissue is different from brain tissue. Since the pituitary gland is located at the base of the brain and is connected to the brain by a thin stalk, there is often confusion, particularly by insurance companies, about the classification of a pituitary tumor. A pituitary tumor is NOT a brain tumor.
3. Is a pituitary tumor cancer?
No, in over 99% of patients, this is NOT a cancer; it is benign. Although the tumor is benign, it can cause problems because of its size, because it causes the normal pituitary gland to become underactive (hypopituitarism) or because of excessive hormone production by the tumor.
4. What are the symptoms of a pituitary tumor?
The symptoms of a pituitary tumor depend on two issues: 1) the size and location of the tumor (tumor mass effects), and 2) whether or not the tumor is producing too much or too little hormone (endocrine function). When a tumor is large enough to compress the optic chiasm (where the optic [eye] nerves come together) there may be loss of vision, particularly peripheral vision. Very occasionally tumors may cause double vision. Headache may also occur; the type of headache varies from patient to patient. Headache may occur with a large or a small tumor.
Some tumors overproduce hormones. The most common of these is a prolactin producing tumor (prolactinoma), followed in frequency by growth hormone producing tumors (acromegaly) and the by ACTH tumors (Cushing’s disease) and rare TSH producing tumors. The overproduction of these hormones causes specific problems (see below and refer to sections on acromegaly and prolactinoma and any articles on these tumors). A tumor may also interfere with normal pituitary function and cause hypothyroidism (low thyroid hormone level), adrenal insufficiency (low cortisol level), hypogonadism (loss of sexual function in men, loss of menstrual periods or fertility problems in women). Very rarely, a pituitary tumor causes diabetes insipidus, which results in frequent urination and excessive thirst. Diabetes insipidus is not high blood sugar levels; it is a problem with the ability of the kidney to retain fluid because of a deficiency of the pituitary hormone, vasopressin (also called antidiuretic hormone). When related to a pituitary tumor diabetes insipidus comes on after an operation to remove the pituitary tumor. Most often diabetes insipidus is related to other another sort of tumor (craniopharyngioma).
Specific types of tumors cause various symptoms and changes in body function.
Prolactinoma: most commonly causes loss of sexual function and infertility in men. Men may also have a breast discharge that looks like milk or occasionally enlargement of the breasts. In women of reproductive age a prolactin-producing tumor may cause milk in the breasts, a change in menstrual periods or loss of menses or infertility. Women who have gone through menopause do not have a change in menstrual periods to signal the problem; in this situation, headache and loss of vision may be the first indicator of a prolactinoma. There can sometimes be impairment of pituitary function leading to growth hormone deficiency, hypothyroidism and adrenal insufficiency as well as the sexual dysfunction referred to above.
Acromegaly: Enlargement of the hands and feet and coarsening of facial features and excessive sweating are the most common features of excessive growth hormone production. Other problems that occur include joint pains and arthritis, sleep apnea (excessive snoring, stopping breathing during sleep and fatigue during waking hours), hypertension, diabetes mellitus (high blood sugar), colon polyps, change in teeth spacing, oily skin and acne. These tumors can also cause tumor mass effect and cause symptoms due to underproduction of hormones (hypothyroidism, adrenal insufficiency, impaired sexual function). Yes, the same tumor that overproduces one hormone may under produce others. Both of these can cause symptoms.
Cushing’s Disease : The term “Cushing’s Disease” refers to the overproduction of cortisol by the adrenal glands caused by a pituitary tumor producing an excessive amount of the pituitary hormone, ACTH. Dr. Harvey Cushing, a neurosurgeon, first described this condition in the 1920s. Excessive cortisol production causes weight gain (particularly in the abdomen and neck), loss of muscle mass (legs, arms) and muscle weakness, depression, difficulty with concentration and memory, sleep disturbance, irritability, thinning of the skin with easy bruising, hypertension, diabetes mellitus, loss of bone mass (osteoporosis) with a risk for bone fractures and weakening of the immune system with a higher risk of developing infections.
Thyroid stimulating hormone (TSH) Secreting Tumor : This is the least common type of hormone producing pituitary tumor. Excessive TSH stimulates the thyroid gland to enlarge (goiter) and also produce an excessive amount of thyroid hormone (hyperthyroidism). This kind of hyperthyroidism is caused by a pituitary tumor overproducing TSH (this is in contrast to the much more common type of hyperthyroidism (Grave’s disease) in which the problem is in the thyroid gland itself). In the latter the TSH is unmeasurably low in contrast to the TSH secreting tumor in which TSH is measurable or high. Symptoms of hyperthyroidism are similar in both kinds of hyperthyroidism and include weight loss, nervousness, rapid heartbeat, difficulty sleeping, frequent bowel movements and in women, less menstrual flow or loss of menstrual periods. As with other functioning pituitary tumors these can also cause symptoms due to the tumor size.
Non Secretory Tumor : This refers to a tumor that does not produce an excessive amount of a pituitary hormone that can be measured in a blood test. This type of tumor is usually discovered when patients develop visual field problems due to the size of the tumor. This type of tumor is usually detected after it has become large, causing loss of vision and/or headache. Frequently as these tumors get bigger the patients have a higher incidence of reduced pituitary function or hypopituitarism, most commonly in the form of sexual dysfunction in men and loss of regular menses and infertility in premenopausal women. Hypothyroidism (low thyroid hormone level) or adrenal insufficiency (low cortisol level) may occur due to partial or complete destruction of the normal cells of the pituitary gland. (See section on hypopituitarism for discussion).
Craniopharyngioma/Rathke’s Cleft Cyst : These tumors are congenital - a defect in the development of the pituitary gland which begins during fetal (in the womb) development. The beginnings of the tumor are present at birth but may not cause a problem until childhood or in adulthood until its size or relationship to important structures in that part of the head causes a problem. In fact, these tumors and cysts may never cause a problem. They are not, however, pituitary tumors. This is not a malignant (cancerous) tumor but it often interferes with normal pituitary function causing hypopituitarism (loss of pituitary function) or headache or loss of vision. This type of tumor commonly causes diabetes insipidus, frequent urination and excessive thirst (not diabetes or high blood sugar).
5. What are other pituitary diseases that can be mistaken for pituitary tumors?
Pituitary Cyst : Any endocrine gland may develop a cyst. This occurs commonly in the ovaries and thyroid gland; a cyst in the pituitary gland is benign (not cancer). Many pituitary cysts cause no symptoms and don’t grow or enlarge. Only when they do, do they become symptomatic. They can cause headache and/or rarely interfere with normal pituitary function. If the cyst is large, loss of vision may occur. The treatment for this problem depends upon the size of the cyst and its proximity to the optic chiasm. Often no treatment is necessary, but when necessary it is removed by surgery. There are no medical treatments for this problem.
Inflammatory Problems: A number of inflammatory problems can lead to either enlargement of the pituitary gland or infiltration into the pituitary or the pituitary stalk or the gland above the pituitary (Hypothalamus).
Lymphocytic hypophysitis is an inflammatory process (rather than a tumor) that can enlarge the pituitary gland and cause pituitary hormone insufficiency. It occurs mostly in women and is often related to a pregnancy. The symptoms can be profound. They include weakness, extreme fatigue, weight loss, and nausea to name a few. The latter symptoms are due to ACTH deficiency, which in turn causes adrenal gland insufficiency. Hypothyroid symptoms also occur and menstrual periods may be interfered with. Sometimes it is not possible to differentiate between hypophysitis and a pituitary tumor on MRI. The pituitary gland can enlarge to cause visual problems and severe headaches. When suspected some endocrinologists have treated these women with cortisone and in some patients the apparent tumor shrinks. Occasionally, there is spontaneous return of normal pituitary function.
Sarcoidosis is an inflammatory disease that usually affects the lungs. Granulomas are inflammatory deposits that have a particular appearance under the microscope. Sarcoidosis can also affect the pituitary gland and hypothalamus. This disease can cause Diabetes Insipidus because it can affect sensitive areas of the pituitary stalk or hypothalamus that control production of the hormone, vasopressin. It can also cause sexual dysfunction or loss of menstruation, hypothyroidism, adrenal insufficiency, or growth hormone deficiency due to actions of the granulomas either in the hypothalamus or pituitary.
Histiocytosis and Eosinophilic Granuloma are rare diseases that can affect the pituitary gland and hypothalamus. They have effects elsewhere in the body, as well. As with sarcoidosis, Diabetes Insipidus is common as is pituitary insufficiency. The disorders themselves are generally treated by specialists for these diseases, while the pituitary issues are managed by neuroendocrinologists.
Pituitary Apoplexy: Pituitary apoplexy is a hemorrhagic disorder of the pituitary. It generally happens in people with pituitary adenomas. It is heralded by a severe headache often together with visual problems. The latter can be double vision or loss of visual fields. Although apoplexy can occur with any sort of pituitary tumor it happens most commonly in non-functioning ones. This is especially true in individuals who were not aware that they had pituitary tumors. A drop in blood pressure can sometimes precede apoplexy. Pituitary apoplexy is a medical emergency. Anyone who develops such symptoms as described above should seek immediate medical attention
6. What is the best treatment for a pituitary tumor?
Pituitary tumors are diagnosed by signs and symptoms, blood tests and X-rays. Depending on the type, size, location, and symptoms, clinical decision must be made as to whether any therapy is necessary and, if so, whether medical, surgical, and radiation therapy alone or in combination are required. In some patients, immediate therapy may not be indicated, in which case it is important to monitor changes in signs and symptoms, blood tests, and X-rays over time.
The best treatment depends on the type of pituitary tumor. Prolactin producing tumors are most successfully treated with medical therapy (pills). In over 90% of patients, medical therapy (pills) reduces tumor size and blood prolactin levels. In approximately 8-10% of patients, medical treatment is not adequately effective and surgery, and rarely, radiation therapy, may be necessary.
The best treatment for other types of pituitary tumors, when surgical treatment is required, is removal of the tumor by an experienced neurosurgeon who performs pituitary surgery frequently. Although most neurosurgeons have some experience with pituitary surgery, only a few have devoted their career to pituitary surgery and have the “best” records of success.
7. If a tumor was successfully removed why are regular visits, blood tests and MRIs necessary?
A minority of patients with pituitary tumors will have a recurrence of the tumor after the initial surgery. Even in the best surgical hands, a significant minority of patients will have a tumor recurrence within 10 years and many will require additional treatment (medical, surgery, pituitary radiation). Since it is not possible to predict which patient’s tumor will recur, all patients need regular medical follow up. Additionally, a tumor may recur 20 years or more after the original treatment. If the tumor was producing a hormone that caused particular symptoms (Cushing’s, Acromegaly, prolactin tumor), the patient is usually the first to recognize this. Measurement of the appropriate hormone level in blood and/or urine is the most accurate method of determining if the tumor has recurred. Non secretory tumors do not produce an excessive hormone that can be measured in the blood or urine and the MRI scan is the best method to follow this condition. In addition, periodic test of normal pituitary function are required in patients with non hormone-secreting tumors as hypopituitarism may be the first sign of tumor regrowth. Furthermore, patients receiving hormone replacement need to be monitored at regular intervals for adequacy of treatment and to learn of the availability of newer forms of therapy.
8. Is radiation necessary in all patients? Who should have radiation treatment to the pituitary?
Radiation to the pituitary is not the first line of treatment for most pituitary tumors. It does not produce an immediate effect to lower excessive hormone production or shrink the tumor. Radiation is used when there is significant tumor remaining after surgery, there are no effective medical therapies for the tumor, or when surgery cannot be performed. Pituitary radiation may take several years to be effective. For example, in patients with acromegaly (excessive growth hormone production), growth hormone levels may remain elevated for 10 to 20 years after conventional radiation.
9. Are all types of pituitary radiation the same?
No. There are different methods of delivering radiation to the pituitary gland. Conventional (fractionated) radiation refers to delivery of a small amount of radiation every day for 4 to 5 weeks. Stereotactic radiation refers to delivery of a precisely focused beam of radiation to the remaining tumor, usually as one treatment (for example, the Gamma Knife, LINEAC, proton beam). The decision as to which type of radiation to administer must be made only after a careful review of the MRI scan to assess the size and location of the residual tumor. A large tumor that is near the optic chiasm (eye nerves) is not suitable for stereotactic radiation because of the intensity (radiation dose) of the single treatment and risk of damage to vision. Stereotactic radiation is reserved for residual tumor that is not near the optic chiasm. Surgery is sometimes needed to remove the portion of the tumor that is near the optic chiasm so that more effective radiation therapy can be given.
10. What are the side effects of radiation?
The most common side effect is loss of normal pituitary function. This may occur within a year or many years after treatment. One study reported that 50% of patients treated with conventional radiation developed deficiency of one or more pituitary hormones within 2 years of treatment. Although development of a pituitary hormone deficiency is not desirable, hormone replacement therapy is available. Every patient treated with radiation, which affects the pituitary or hypothalamus is at risk for the development of loss of pituitary function. Therefore, periodic blood tests are required. An uncommon side effect is damage to vision. In small number of patients, another type tumor, which may be malignant, may develop in the area where radiation was given. Patients receiving conventional radiation may also be at increased for stroke. The risk associated with newer forms of radiation is not yet known. These risks must be weighed against the risk of tumor re-growth. Hair loss does not usually occur.
11. Does a pituitary tumor shorten life?
Having a pituitary tumor should not shorten life if it is properly treated and if the patient receives appropriate hormone replacement(s). In large population studies, it appears that patients who had conventional, radiation for pituitary tumors had an increased mortality (death) risk because of cerebrovascular disease (stroke).
Pituitary hormone deficiency requires hormone(s) replacement. All medications must be taken as directed. Additionally, there is a need for regular medical care and monitoring of medical treatments. Most patients who have had a pituitary tumor engage in normal work and social activities. If a patient requires steroid (cortisol) replacement, a Medical alert bracelet or necklace should be worn at all times. Another illness such as the flu, pneumonia or an accident requires an increase in the steroid dose. If the patient is brought to the hospital and unable to give the medical history, the physicians will have no way of knowing that additional steroid is necessary. With attention to these important details, a patient with a pituitary tumor should have a full and productive life.
Patients with uncontrolled Acromegaly (growth hormone producing tumor) or Cushing’s disease (excessive cortisol production) do have an increased risk of dying earlier than expected and for having complications of the hormone excess. Lowering of the excessive hormone level to normal reduces this risk. Complications associated with pituitary tumors include:
Acromegaly: heart failure, high blood pressure, abnormal lipids (cholesterol), diabetes, snoring and other sleep-related breathing problems, joint disease, loss of reproductive function, infertility, colon polyps (benign growths) and possibly color cancer.
Cushing’s disease: heart disease, abnormal lipids, diabetes, high blood pressure, osteoporosis and bone fractures, depression and suicide risk, memory loss, muscle weakness, reproductive disorders, infertility, and susceptibility to infection.
Prolactinoma : high prolactin is not known to shorten life; however loss of normal testosterone production in men causes osteoporosis and increases the risk for bone fractures. This also occurs in women who have loss of regular menstrual cycles. Non-functioning adenoma, Craniopharyngioma, Rathke’s Cleft cyst, pituitary cyst: There is no known risk of premature death as long as appropriate hormone replacement(s) are taken. Complications are related to the adequacy of hormone replacement(s).
Share This
