Pituitary Tumors

Pituitary Tumors

 

Definition

Pituitary tumors are abnormal growths on the pituitary gland. Some tumors secrete hormones normally made by the pituitary gland.

Description

Located in the center of the brain, the pituitary gland manufactures and secretes hormones that regulate growth, sexual development and functioning, and the fluid balance of the body. About 10% of all cancers in the skull are pituitary tumors. Pituitary adenomas (adenomas are tumors that grow from gland tissues) and pituitary tumors in children and adolescencents (craniopharyngiomas) are the most common types of pituitary tumors. They are usually benign and grow slowly. Even malignant pituitary tumors rarely spread to other parts of the body.
Pituitary adenomas do not secrete hormones but are likely to be larger and more invasive than tumors that do. Craniopharyngiomas are benign tumors that are extremely difficult to remove. Radiation does not stop them from spreading throughout the pituitary gland. Craniopharyngiomas account for less than 5% of all brain tumors. Pituitary tumors usually develop between the ages of 30 and 40, but half of all craniopharyngiomas occur in children, with symptoms most often appearing between the ages of five and ten.

Causes and symptoms

The cause of pituitary tumors is not known, but may be genetic. Symptoms related to tumor location, size, and pressure on neighboring structures include:
  • persistent headache on one or both sides, or in the center of the forehead
  • blurred or double vision; loss of peripheral vision
  • drooping eyelid caused by pressure on nerves leading to the eye
  • seizures
Symptoms related to hormonal imbalance include:
  • excessive sweating
  • loss of appetite
  • loss of interest in sex
  • inability to tolerate cold temperatures
  • nausea
  • high levels of sodium in the blood
  • menstrual problems
  • excessive thirst
  • frequent urination
  • dry skin
  • constipation
  • premature or delayed puberty
  • delayed growth in children
  • galactorrea (milk secretion in the absence of pregnancy or breast feeding)
  • low blood pressure
  • low blood sugar

Diagnosis

As many as 40% of all pituitary tumors do not release excessive quantities of hormones into the blood. Known as clinically nonfunctioning, these tumors are difficult to distinguish from tumors that produce similar symptoms. They may grow to be quite large before they are diagnosed.
Endocrinologists and neuroendocrinologists base the diagnosis of pituitary tumors on:
  • the patient's own observations and medical history
  • physical examination
  • laboratory studies of the patient's blood and cerebrospinal fluid
  • x rays of the skull and other studies that provide images of the inside of the brain (CT, MRI)
  • vision tests
  • urinalysis

Treatment

Some pituitary tumors stabilize without treatment, but a neurosurgeon will operate at once to remove the tumor (adenectomy) or pituitary gland (hypophysectomy) of a patient whose vision is deteriorating rapidly. Patients who have pituitary apoplexy may experience very severe headaches, have symptoms of stiff neck, and sensitivity to light. This condition is considered an emergency. Magnetic resonance imaging (MRI) is the best imaging technique for patients with these symptoms. If the tumor is small, surgery may be done through the nose. If the tumor is large, it may require opening the skull for tumor removal. Selected patients do well with proton beam radiosurgery (the use of high energy particles in the form of a high energy beam to destroy an overactive gland).
Treatment is determined by the type of tumor and by whether it has invaded tissues adjacent to the pituitary gland. Hormone-secreting tumors can be successfully treated with surgery, radiation, bromocriptine (Parlodel), Sandostatin (Octreotide), or other somatostatin analogues (drugs similar to somatostatin). Surgery is usually used to remove all or part of a tumor within the gland or the area surrounding it, and may be combined with radiation therapy to treat tumors that extend beyond the pituitary gland. Removal of the pituitary gland requires life-long hormone replacement therapy.
Radiation therapy can provide long-term control of the disease if it recurs after surgery, and radioactive pellets can be implanted in the brain to treat craniopharyngiomas. CV205-502, a new dopamine agonist (a drug that increases the effect of another, in this instance dopamine) can control symptoms of patients who do not respond to bromocriptine.

Prognosis

Pituitary tumors are usually curable. Following surgery, adults may gradually resume their normal activities, and children may return to school when the effects of the operation have diminished, and appetite and sense of well-being have returned. Patients should wear medical identification tags identifying their condition and the hormonal replacement medicines they take.

Resources

Organizations

American Brain Tumor Association. 2770 River Road, Des Plaines, IL 60018. (800) 886-2289. 〈http://www.abta.org〉.
Brain Tumor Information Services. Box 405, Room J341, University of Chicago Hospitals, 5841 S. Maryland Ave., Chicago, IL 60637. (312) 684-1400.

Key terms

Agonist — A drug that increases the effectiveness of another drug.
Analogue — A drug that is similar to the drug from which it is derived.
References in periodicals archive ?
The absence of a prognostic classification or consensual prognostic markers limits the evaluation of medical strategies for pituitary tumors.
This impressive group of experts shows how complex and demanding this field of medicine is, with a note that Dr Zivko Gnjidic and Professor Biserka Belicza from Department of History of Medical Sciences, Croatian Academy of Sciences and Arts wrote the chapter entitled Pregled povijesnih zbivanja u podrucju dijagnostike i lijecenja tumora hipofize (Historical Review of Diagnosis and Treatment of Pituitary Tumors), in which they present data on the history of treatment of pituitary tumors in our Hospital, as reported in the Historical Review in this issue.
2013 European thyroid association guidelines for the diagnosis and treatment of thyrotropin-secreting pituitary tumors.
Researchers at NIH's Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), in collaboration with researchers at other institutions in the United States, France, and Canada, scanned tumor and cell tissue from 146 children with pituitary tumors evaluated for Cushing syndrome at the NIH Clinical Center.
Researchers at NIHs Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), in collaboration with researchers at other institutions in the United States, France and Canada, scanned tumor and cell tissue from 146 children with pituitary tumors evaluated for Cushing syndrome at the NIH Clinical Center.
Use of IGF-I for monitoring of patients during the first days following surgical resection of pituitary tumors, however, is hampered by limited information on the time course of its decrease following resection of GH-producing pituitary tumors (9-11).
Pituitary tumors may lead to symptoms in one or both eyes especially when their sizes exceed 1 cm.
His team is conducting a series of complex projects involving pituitary tumors, gliomas and meningiomas (brain tumors that put pressure on the spinal cord and usually require immediate treatment), and each project has a team dedicated solely to a specific subject.
Criteria for disease control were total tumor removal in non-functioning and hormonal control in functioning pituitary tumors.
They discuss hypothalamic function and pathophysiology, including vasopressin, oxytocin, and corticotropin-releasing hormone and neuroendocrine regulation, stress and water metabolism, and their role as mediators of emotional and social behaviors; new developments in disorders of the pituitary gland, including active and inactive adenomas, Rathke's cleft cysts, craniopharyngioma, and unusual forms of hypopituitarism; and controversial issues like Nelson syndrome, familial pituitary tumors, and autoimmune hypophysitis, as well as central adrenal insufficiency, hypothyroidism, growth hormone deficiency, the irreversible consequences of pituitary tumors and their treatment on quality of life and neuropsychologic function, and neuroendocrine mechanisms in adaptation to exercise.
The Gamma Knife also effectively treats other neurological disorders, such as benign brain tumors, pituitary tumors, primary malignant brain tumors, brain arteriovenous malformations (AVMs), trigeminal neuralgia and acoustic neuromas.