eMedicine Specialties > Neurology > Neuro-oncology

Pituitary Tumors

Author: Jorge Kattah, MD, Head, Program Director, Professor, Department of Neurology, University of Illinois College of Medicine at Peoria
Contributor Information and Disclosures

Updated: Jan 14, 2009

Introduction

Background

Pierre Marie, a French neurologist (Salpetriere Hospital, Paris) was the first to describe a disease that involved the pituitary gland. In 1886, he studied 2 patients with clinical findings of what he termed acromegaly and postulated that the pituitary gland was involved in the pathogenesis.

Pituitary tumors are common neoplasms, and recognition of their presentation is critical since a favorable therapeutic outcome is dependent on early identification of the lesion.

Pathophysiology

Most of these tumors are benign, but certain factors involved in the genesis of the tumor may determine its rate of growth and aggressiveness. For instance, the presence of p53 correlates with more aggressive tumor behavior.

Clinical manifestations are due to the local effect of the mass and distant endocrine manifestations that can affect a variety of organ systems. These effects are due to lack or excess of a given stimulating hormone on the target organ. Pituitary adenomas, with a few exceptions, are not under the control of hypothalamic releasing factors.

Classification of pituitary tumors

Based on size, pituitary tumors can be divided into microadenomas (<1 cm diameter) and macroadenomas (>1 cm diameter). They also can be classified on the basis of staining characteristics, as chromophobic and chromophilic tumors. The latter can be further subdivided using hematoxylin and eosin stains (ie, eosinophilic or basophilic).

However, this classification has proven to be of no clinical value and now has been replaced by a more functional classification that involves electromicroscopy and immunohistochemistry. These techniques have identified hormonal production in many chromophobe adenomas, enabling pathologists to identify hormones that are produced by eosinophilic tumors. They also have demonstrated that many tumors produce more than one hormone. The mutated form of p53, a tumor suppressor, also can be determined histologically. The presence of this mutated gene suggests a tumor with rapid growth.

The endocrinologic morbidity that is associated with pituitary tumors is dependent on the specific underproduction or overproduction of a hormone or hormones associated with the tumor.

Hormonal deficiencies - Clinical effects

Growth hormone deficiency

• Adults - Increased rate of cardiovascular disease, obesity, reduced muscle strength and exercise capacity, and increased cholesterol
• Infants - Hypoglycemia
• Children - Decreased height and growth rate

Gonadotrophin deficiency

• Men - Diminished libido and impotence; testes shrink in size, but spermatogenesis generally preserved
• Women - Diminished libido and dyspareunia; breast atrophy in chronic deficiency
• Children - Delayed or frank absence of puberty
• Adolescent girls - Present similarly to adult women

Thyrotropin deficiency - Malaise, weight gain, lack of energy, cold intolerance, and constipation

Corticotrophin deficiency

• Unlike primary adrenal insufficiency, mineralocorticoid function (which is dependent on the angiotensin-renin axis) not affected; deficiency limited to glucocorticoids and adrenal androgens
• Initially, symptoms nonspecific (eg, weight loss, lack of energy, malaise); severe adrenal insufficiency may present as a medical emergency

Panhypopituitarism - Refers to deficiency of several anterior pituitary hormones; may occur in a slowly progressive fashion (eg, pituitary adenomas)

Hormonal overproduction - Clinical effects

Prolactin

• Hypogonadism, if hyperprolactinemia sustained
• Women - Amenorrhea, galactorrhea, and infertility
• Men - Decreased libido, impotence, and rarely galactorrhea

Growth hormone

• Children and adolescents - May result in pituitary gigantism
• Adults - Acromegaly
  • Changes in the size of the hand and feet, coarseness of the face, frontal bossing, and prognathism result. Further changes in the voice, and hirsutism, confirm the diagnosis.
  • Acromegaly frequently results in glucose intolerance, with 20% of patients progressing to diabetes mellitus.
  • Respiratory difficulty and sleep apnea are fairly common.
  • Cardiac complications result from acromegalic cardiomyopathy.
  • Although patients have a bulky appearance, they are generally weak as a result of associated myopathy.
  • Carpal tunnel syndrome is seen frequently.
  • Lumbar canal stenosis can present with a syndrome resembling amyotrophic lateral sclerosis.
  • Acromegaly may be associated with colonic polyps, although an increased colon cancer incidence has not been shown definitively.

Cushing disease

• Weight gain, centripetal obesity, moon facies, violet striae, easy bruisability, proximal myopathy, and psychiatric changes
• Other possible effects - Arterial hypertension, diabetes, cataracts, glaucoma, and osteoporosis

Frequency

United States

Pituitary tumors represent anywhere between 10% and 15% of all intracranial tumors.

Incidental pituitary tumors are found in approximately 10% of autopsies.

The incidence of acromegaly is approximately 3 per million. Acromegaly has no sex predilection.

International

The incidence of pituitary tumors is probably the same worldwide.

Mortality/Morbidity

• Mortality rate related to pituitary tumors is low. Advances in medical and surgical management of these lesions and the availability of hormonal replacement therapies have contributed to successful management.
• Pituitary apoplexy can be a lethal complication.
• Morbidity associated with macroadenomas may include permanent visual loss, ophthalmoplegia, and other neurological complications.
• Tumor recurrence is also a possibility.
• CNS metastases and, rarely, distant metastases occur with pituitary tumors.
• Endocrine abnormalities are amenable to correction. However, damage in many organ systems as a result of long-standing uncorrected deficiencies may be irreversible.

Race

No racial predilection is known.

Sex

• Symptomatic prolactinomas are found more frequently in women.
• Cushing disease also is more frequent in women (female-to-male ratio 3:1).

Age

• Most pituitary tumors occur in young adults, but they may be seen in adolescents and elderly persons.
• Acromegaly usually is seen in the fourth and fifth decades of life.

Clinical

History

• The presentation of a pituitary macroadenoma relates to its mass effect and pressure on surrounding structures.
• Fifty to sixty percent present with visual symptoms due to compression of optic nerve structures.
• Nonspecific headache can be seen.
• Lateral extension can result in compression of the cavernous sinuses and may cause ophthalmoplegia, diplopia, and/or ptosis. Talkad et al recently reported an isolated, painful, postganglionic Horner syndrome as the initial sign of lateral extension of a large prolactinoma.²
• Extension into the sphenoid sinuses can cause spontaneous cerebrospinal fluid (CSF) rhinorrhea.
• In addition to visual symptoms, endocrine dysfunction, as described in Pathophysiology, can result.

Physical

Macroadenomas can compress optic nerve structures. The optic chiasm is the most frequently affected structure, and bitemporal field defects are the most common findings.

• Neuro-ophthalmologic examination
  • Visual acuity can be decreased in one or both eyes.
  • Pupillary light reaction can be abnormal.
  • Color vision can be affected. Bitemporal hemiachromatopsia to red may be localized to the optic chiasm. This can be tested easily at bedside.
  • Visual fields
    • The hallmark abnormality associated with chiasmal compression is a bitemporal superior quadrantanopsia.
    • Larger lesions may be associated with a bitemporal hemianopsia.
    • Since the optic chiasm is usually adjacent to the tuberculum sellae, chiasmal compression is seen commonly.
    • Less frequently, the chiasm may be anterior or posterior to the tuberculum sellae (ie, prefixed or postfixed chiasm). Thus, the pattern of visual field defect can be variable. Any form of temporal field defect, even if monocular, can result from chiasmal compression.
    • The anterior chiasmal syndrome is not caused often by pituitary adenomas. However, bitemporal scotomata and, infrequently, homonymous defects due to optic tract compression may be seen.
• Ophthalmoscopic examination
  • Optic atrophy is seen frequently. It is generally a horizontal-oriented atrophy (ie, bow-tie) that corresponds to the topographic localization of the nasal retina within the optic nerve. Dropout of the nerve fiber layer in the nasal retina also may be noted.
  • Papilledema is exceptional, seen only in patients with pituitary apoplexy.
  • Less frequent optic atrophy with increased cup-to-disk ratio resembling glaucomatous optic atrophy can occur.
• These abnormalities may be present in isolation or in association with physical changes associated with endocrine dysfunction.
  • Prolactinomas
    • In females, galactorrhea may be present on clinical examination. Women undergoing an infertility evaluation may be found to have a prolactinoma.
    • In males, galactorrhea is infrequent; testicles may be decreased in size and may be soft to palpation.
  • Acromegaly
    • A multitude of clinical signs can be appreciated by comparing the current facial appearance with prior photographs.
    • These changes include large hands and feet (with thick fingers and toes) and coarse facial features with frontal bossing. Women may appear masculinized. Other findings might include prognathism, carpal tunnel syndrome, and voice quality changes.
  • Cushing disease: Findings are prominent and include obesity, centripetal fat deposition, proximal myopathy, moon facies, buffalo hump, posterior subcapsular cataracts, arterial hypertension, bruises, and skin striae.
  • Hypopituitarism
    • Chronic hypopituitarism results in hypotension, generalized weakness, hypothermia, malaise, and depression.
    • Acute sudden hypopituitarism (ie, pituitary apoplexy) is associated with shock, coma, and death.

Causes

See Pathophysiology.

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