Pituitary adenomas are slow-growing tumors that arise from the pituitary gland, located at the base of the skull. Patients may experience headaches, vision defects, and specific symptoms related to abnormal hormone deficit or excess. Treatment options include medications in some cases, surgery, and radiation. Survival is usually excellent; however, the effectiveness of treatment depends on the specific type of tumor.
What Is a Pituitary Tumor/Adenoma?
Pituitary tumors are most commonly benign tumors associated with one of the body's most prominent hormone-secreting structures—the pituitary gland. Pituitary tumors are slow-growing, non-cancerous, and will not spread to other parts of the central nervous system or body.
Figure 1. Cross-section of a pituitary tumor at the base of skull.
Pituitary tumors represent up to one-fourth of all brain tumors. These tumors may or may not secrete a variety of hormones on their own. The pituitary tumors that secrete a hormone are referred to as functioning tumors, whereas those that do not secrete a hormone are classified as nonfunctioning tumors. Pituitary tumors are commonly referred to as pituitary adenomas.
What Is the Pituitary Gland?
The pituitary gland is located between your eyes and in the middle of the head at the base of skull. It plays an important role in hormonally regulating a wide variety of body functions, such as growth, metabolism, sexual reproduction, water retention, and the body's stress response. The stalk-like pituitary gland is surrounded by major arteries (the carotid arteries), the optic (eye) nerves, and important brain structures such as the hypothalamus, which is responsible for regulating many of the body's homeostatic (stabilizing) regulatory systems (including the pituitary gland).
What Are the Symptoms?
The symptoms associated with pituitary tumors are generally a result of altered hormonal function and/or increased local pressure on the optic (eye) nerves caused by the tumor. Symptoms vary widely and depend on whether hormone secretion is altered, what kind of hormone is affected and overproduced, and which structures experience abnormal pressure and compression from the tumor.
Symptoms may be caused by pressure on surrounding structures such as the optic nerves or hypothalamus or from decreased hormone output from the increased pressure on the pituitary gland itself.
- Temperature sensitivity
- Excessive perspiration
- Decreased appetite
- Double, blurred, and/or poor peripheral vision
- Nausea and vomiting
- Decreased libido
- Menstrual disorders
- Excessive thirst/frequent urination
- High or low blood pressure
- Slow growth
- Late- or early-onset puberty
Other symptoms can result from excessive levels of one of the following hormones:
- Irregular or absent menstruation
- Decreased libido
- Production of milk and abnormal discharge from the nipples (galactorrhea)
- Vaginal dryness
- Erectile dysfunction
- Growth hormone
- Enlargement of the hands, feet, face, tongue, and/or other soft tissues
- Coarsening of facial features
- Sleep apnea
- Facial paralysis on one side
- Carpal tunnel syndrome
- Joint and bone pain
- Abnormal or excessive perspiration
- Oily skin
- Adrenocorticotropic hormone
- Rapid weight gain, particularly in the torso and face out of proportion to the limbs
- Insulin resistance leading to hyperglycemia and diabetes
- Thin and weakened skin that is prone to bruising
- Striae of the skin (lines/wrinkles/stretch marks)
- Hirsutism (facial and male-pattern hair growth)
- Psychological symptoms such as mood swings, depression, and anxiety
- Weakened muscles and bones
- Decreased fertility in men
- Thyroid stimulating hormone
- Increased appetite
- Weight loss
- Irregular heartbeat
- Muscle weakness
- Abnormally frequent bowel movements
- Swelling in the lower extremities
- Decreased fertility
- Excessive sweating
What Are the Causes?
The cause of pituitary tumors is currently unknown. Certain rare heritable conditions such as multiple endocrine neoplasia type 1 (MEN1) increases the risk of developing a pituitary tumor. However, most tumors develop spontaneously and are not associated with any hereditary conditions.
How Common Is It?
Pituitary tumors are the second most common benign primary tumor of the central nervous system and account for 17% of all such tumors. The incidence rate is 4.20 per 100,000 population. Females tend to be diagnosed with a pituitary tumor more often than males. Pituitary tumors are more common in older patients.
How Is It Diagnosed?
Diagnosis is based on a variety of factors, including the clinical history, physical examination, and laboratory/radiological findings. Your doctor will begin by taking a history to identify possible symptoms of pituitary disorders and eliminate alternative diagnoses. A physical examination is usually done to identify deficits in vision or changes in appearance that may be attributed to a pituitary tumor (Please see the changes associated with each hormonal imbalance above.)
Depending on what is found, the doctor may order a variety of tests:
- Blood and/or urine tests to identify excessive or insufficient hormone levels
- Magnetic resonance imaging (MRI) or, less often, computed tomography (CT) imaging is performed to image the presence of a tumor
- Venous blood sampling can be used to detect adrenocorticotropic hormone-secreting tumors that are difficult to identify with MRI
- In rare cases, biopsy of the tumor may be conducted if further identification is necessary
Figure 2. Large pituitary adenoma (white) pressing against the optic chiasm, which would lead to visual defects.
What Are the Treatment Options?
Treatment options vary depending on the tumor type, size, and degree to which the tumor interferes with the surrounding structures. Treatment options include medication, surgery, and radiation. Pituitary tumors that are discovered incidentally and do not cause symptoms may be observed over time.
A variety of medications can be used to decrease the production of a specific hormone by the tumor or block the effect of that hormone on the body's tissues. Additional medications may be used to substitute for low hormone production. Prolactin-secreting tumors (called prolactinomas) usually shrink with medical therapy, negating the need for surgery.
Surgery is the primary form of treatment for most pituitary tumors except for prolactin-secreting tumors. The type of surgery and its chance of success depend on the tumor’s size, location, and overall invasiveness.
Transsphenoidal surgery is a technique that uses an endoscope to enter the skull through the nose to remove the tumor, eliminating the need for a larger incision via a craniotomy. This is the preferred method for small, medium, and some large tumors. There is no visible scar, and no part of the brain is directly touched. This technique therefore minimizes neurological complications.
Figure 3. Endonasal approach to a pituitary tumor.
Complication rates are low but can include cerebrospinal fluid leak, excessive urination and thirst (diabetes insipidus), and hormone deficits. These are often temporary conditions. Most hospital stays are no longer than 1 to 2 days.
Some larger tumors usually cannot be removed in the same way. In such instances, the surgeon might opt for a craniotomy. During this procedure, the surgeon exposes the tumor through the upper portion of the skull. This is a more invasive form of surgery, and postoperative stays are longer, usually between 3 and 4 days.
Radiation therapy is often used after surgery to prevent growth of the residual tumor. If there is evidence of growth of the residual tumor after surgery, radiation treatment might be considered. Radiation therapy can come in the form of traditional external-beam radiation or via the more intense and precise stereotactic radiosurgery.
Traditional external-beam radiation therapy directly delivers a single beam of radiation to the tumor. The procedure is usually performed 5 times per week, for several weeks. The radiation treatments can take several years to bring tumor growth and/or hormone secretion under full control, and the procedure risks damaging normal pituitary function as well as adjacent neural structures.
Stereotactic radiosurgery can deliver higher doses of radiation more accurately by applying precise and multiple beams to target the tumor. It does not require any incision and is done as a single-session outpatient procedure. As with external-beam radiation therapy, it may take years for the full benefits to manifest, but unlike external-beam radiation therapy, surrounding structures are less prone to damage from the radiation treatment. Treatment is usually avoided for tumors near important nerves.
Radiation therapy can be used rarely as an alternative to surgery for cases in which the tumor is inaccessible via traditional routes.
Possible complications of radiation therapy include headaches, seizures, neurologic problems (depending on the area being treated), and difficulties with thinking or decision-making. Permanent injury to healthy tissues caused by radiation (radiation necrosis) is another possible but delayed complication of radiotherapy that results in headaches, memory loss, personality changes, and seizures. This complication is rare but can occur months to years after treatment.
What Is the Recovery Outlook?
Most pituitary tumors are benign and slow-growing (noncancerous). However, the tumors that produce certain hormones can have long-term side effects that expose the patient to risk of heart attack or stroke. Although usually not life-threatening, larger tumors can compress or even invade surrounding structures. The removal of these tumors is more challenging, and they have a higher tendency to recur.
Central nervous system—brain and spinal cord
Cerebrospinal fluid—clear fluid surrounding the brain and spinal cord
Dura—outermost layer of the meninges
Edema—swelling caused by excess fluid in tissues
Meninges—outer membranous covering of the brain and spinal cord
Contributor: Gina Watanabe BS
- Molitch ME. Diagnosis and treatment of pituitary adenomas: a review. JAMA 2017;317:516–524. doi.org/10.1001/jama.2016.19699
- Ostrom QT, Patil N, Cioffi G, et al. CBTRUS statistical report: primary brain and other central nervous system tumors diagnosed in the United States in 2013–2017. Neuro-Oncology 2020;22(Suppl 1):iv1–iv96. doi.org/10.1093/neuonc/noaa200
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