Pituitary tumors, which constitute 10% of intracranial malignant neoplasms, usually originate in the anterior pituitary (adenohypophysis). They occur in adults of both sexes, usually during the 3rd and 4th decades of life. The three tissue types of pituitary tumors are chromophobe adenoma (90%), basophil adenoma, and eosinophil adenoma.
The prognosis for patients with this type of tumor is fair to good, depending on the extent to which the tumor spreads beyond the sella turcica.
Although the exact cause is unknown, a predisposition to pituitary tumors may be inherited through an autosomal dominant trait. Pituitary tumors aren't malignant in the strict sense but, because their growth is invasive, they're considered a neoplastic disease.
Chromophobe adenoma may be associated with production of corticotropin, melanocyte-stimulating hormone, growth hormone (GH), and prolactin; basophil adenoma, with evidence of excess corticotropin production and, consequently, with signs of Cushing's syndrome; eosinophil adenoma, with excessive GH.
Pituitary tumors develop in 1 in 10,000 people. About 15% of tumors located within the skull are pituitary tumors.
As pituitary adenomas grow, they replace normal glandular tissue and enlarge the sella turcica, which houses the pituitary gland. The resulting pressure on adjacent intracranial structures produces these typical clinical manifestations:
Neurologic:
❑frontal headache
❑ visual symptoms, beginning with blurring and progressing to field cuts (hemianopias) and then unilateral blindness
❑ cranial nerve involvement (III, IV, VI) from lateral extension of the tumor, resulting in strabismus; double vision, with compensating head tilting and dizziness; conjugate deviation of gaze; nystagmus; lid ptosis; and limited eye movements
❑ increased intracranial pressure (ICP) (secondary hydrocephalus)
❑ personality changes or dementia, if the tumor breaks through to the frontal lobes
❑ seizures
❑ rhinorrhea, if the tumor erodes the base of the skull
❑ pituitary apoplexy secondary to hemorrhagic infarction of the adenoma. Such hemorrhage may lead to both cardiovascular and adrenocortical collapse.
Endocrine:
❑ hypopituitarism, to some degree, in all patients with adenoma, becoming more obvious as the tumor replaces normal gland tissue (signs and symptoms include amenorrhea, decreased libido and impotence in men, skin changes [waxy appearance, decreased wrinkles, and pigmentation], loss of axillary and pubic hair, lethargy, weakness, increased fatigability, intolerance to cold, and constipation [because of decreased corticotropin and thyroid-stimulating hormone production])
❑ addisonian crisis, precipitated by stress and resulting in nausea, vomiting, hypoglycemia, hypotension, and circulatory collapse
❑ diabetes insipidus, resulting from extension to the hypothalamus
❑ prolactin-secreting adenomas (in 70% to 75%), with amenorrhea and galactorrhea
❑ GH-secreting adenomas, with acromegaly
❑ corticotropin-secreting adenomas, with Cushing's syndrome.
❑Skull X-rays with tomography show enlargement of the sella turcica or erosion of its floor; if GH secretion predominates, X-rays show enlarged paranasal sinuses and mandible, thickened cranial bones, and separated teeth.
❑ Carotid angiogram shows displacement of the anterior cerebral and internal carotid arteries if the tumor mass is enlarging; it also rules out intracerebral aneurysm.
❑ Computed tomography scan may confirm the existence of the adenoma and accurately depict its size.
❑ Cerebrospinal fluid (CSF) analysis may show increased protein levels.
❑ Endocrine function tests may contribute helpful information, but results are commonly ambiguous and inconclusive.
❑ Magnetic resonance imaging differentiates healthy, benign, and malignant tissues as well as arteries and veins.
Surgical options include transfrontal removal of large tumors impinging on the optic apparatus and transsphenoidal resection for smaller tumors confined to the pituitary fossa. (See Transsphenoidal pituitary surgery.)
Radiation is the primary treatment for small, nonsecretory tumors that don't extend beyond the sella turcica or for patients who may be poor postoperative risks; otherwise, it's an adjunct to surgery.
Postoperative treatment includes hormone replacement with cortisone, thyroid, and sex hormones; correction of electrolyte imbalance; and, as necessary, insulin therapy.
Drug therapy may include bromocriptine, an ergot derivative that shrinks prolactin- and GH-secreting tumors. Cyproheptadine, an antiserotonin drug, can reduce increased corticosteroid levels in the patient with Cushing's syndrome.
Adjuvant radiation therapy is used when only partial removal of the tumor is possible. Cryohypophysectomy (freezing the area with a probe inserted by transsphenoidal route) is a promising alternative to surgical dissection of the tumor.
❑Conduct a comprehensive health history and physical assessment to establish the onset of neurologic and endocrine dysfunction and provide baseline data for later comparison.
❑Establish a supportive, trusting relationship with the patient and his family to assist them in coping with the diagnosis, treatment, and potential long-term changes. Make sure they understand that the patient needs lifelong evaluations and, possibly, hormone replacement.
❑Reassure the patient that some of the distressing physical and behavioral signs and symptoms caused by pituitary dysfunction (for example, altered sexual drive, impotence, infertility, loss of hair, and emotional instability) will disappear with treatment.
❑Maintain a safe, clutter-free environment for the visually impaired or acromegalic patient. Reassure him that he'll probably recover his sight.
❑Position patients who have undergone supratentorial or transsphenoidal hypophysectomy with the head of the bed elevated about 30 degrees to promote venous drainage from the head and reduce cerebral edema. Place the patient on his side to allow drainage of secretions and prevent aspiration.
❑Withhold oral fluids, which can cause vomiting and subsequent increased ICP. Don't allow a patient who has had transsphenoidal surgery to blow his nose. Watch for CSF drainage from the nose. Monitor for signs of infection from the contaminated upper respiratory tract. Make sure the patient understands that he'll lose his sense of smell.
❑Regularly compare the patient's postoperative neurologic status with your baseline assessment. (See Postcraniotomy care.)
❑Monitor intake and output to detect fluid and electrolyte imbalances.
❑Before discharge, encourage the patient to purchase and wear a medical identification bracelet or necklace that identifies his hormone deficiencies and their proper treatment.
Review other book chapters online related to Pituitary tumors, adult:
Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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More About This Book:
Title: Professional Guide to Diseases (Eighth Edition) Authors: Springhouse Publisher: Lippincott Williams & Wilkins Copyright: 2005 ISBN: 1-58255-370-X 
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