Pituitary adenoma


Pituitary adenoma
Pituitary adenoma
Classification and external resources
ICD-10 D35.2
ICD-9 237.0
ICD-O: M8140/0
MedlinePlus 000704
eMedicine neuro/312
MeSH D010911

Pituitary adenomas are tumors that occur in the pituitary gland, and account for about 15% of intracranial neoplasms. They often remain undiagnosed, and small pituitary tumors have an estimated prevalence of 16.7% (14.4% in autopsy studies and 22.5% in radiologic studies).[1][2]

Contents

Types

Pituitary tumors were, historically, classed as basophilic, acidophilic, or chromophobic on the basis of whether or not they took up the stains hematoxylin and eosin. This classification has fallen into disuse, in favor of a classification based on what type of hormone is secreted by the tumor (though tumors which do not secrete any active hormone ("non-functioning tumors") are still sometimes called "chromophobic").

At present, classification of pituitary tumors is based on plasma hormone levels or immunohistochemical staining, as given in table below. The "Percentage of hormone production cases" values are the fractions of adenomas producing each related hormone of each tumor type as compared to all cases of pituitary tumors, and does not directly correlate to the percentages of each tumor type because of smaller or greater incidences of absence of secretion of the expected hormone. Thus, nonsecretive adenomas may be either null cell adenomas or a more specific adenoma that, however, remains nonsecretive.

Type of adenoma Secretion Staining Pathology Percentage of hormone production cases
lactotrophic adenomas or prolactinomas (most common) secrete prolactin acidophilic galactorrhea, hypogonadism, amenorrhea, infertility, and impotence 30%[3]
somatotrophic adenomas secrete growth hormone (GH) acidophilic acromegaly (gigantism) 15%[3]
corticotrophic adenomas secrete adenocorticotropic hormone (ACTH) basophilic Cushing's disease
gonadotrophic adenomas secrete luteinizing hormone (LH), follicle-stimulating hormone (FSH) and their subunits basophilic usually doesn't cause symptoms 10%[3]
thyrotrophic adenomas (rare) secrete thyroid-stimulating hormone (TSH) basophilic to chromophobic occasionally hyperthyroidism,[4] usually doesn't cause symptoms Less than 1%[3]
null cell adenomas do not secrete hormones may stain positive for synaptophysin 25% of pituitary adenomas are nonsecretive[3]

Pituitary incidentalomas

Pituitary incidentalomas are pituitary tumors that are characterized as an incidental finding. They are often discovered by computed tomography (CT) or MRI performed in the evaluation of unrelated medical conditions such as suspected head trauma, cancer staging or in the evaluation of nonspecific symptoms such as dizziness and headache. It is not uncommon for them to be discovered at autopsy. In a meta-analysis, adenomas were found in an average of 16.7% in postmortem studies, with most being microadenomas (<10mm); macrodenomas accounted for only 0.16% to 0.2% of the decedents.[5]While pituitary microadenomas are generally considered benign the presence of a microadenoma has been positively identified as a risk factor for suicide in a postmortem study of suicide victims.[6][7]

Symptoms

Hormone secreting pituitary adenomas cause one of several forms of hyperpituitarism. The specifics depend on the type of hormone. Some tumors secrete more than one hormone, the most common combination being GH and prolactin.

In addition, a pituitary adenoma may present with visual field defects, classically bitemporal hemianopia. It arises from the compression of the optic nerve by the tumor. The specific area of the visual pathway at which compression by these tumours occurs is at the optic chiasma.

The anatomy of this structure causes pressure on it to produce a defect in the temporal visual field on both sides, a condition called bitemporal hemianopia. If originating superior to the optic chiasm, more commonly in a craniopharyngioma of the pituitary stalk, the visual field defect will first appear as bitemporal inferior quadrantanopia, if originating inferior to the optic chiasm the visual field defect will first appear as bitemporal superior quadrantanopia. Lateral expansion of a pituitary adenoma can also compress the abducens nerve, causing a lateral rectus palsy.

Also, a pituitary adenoma can cause symptoms of increased intracranial pressure.

Prolactinomas often start to give symptoms especially during pregnancy, when the hormone progesterone increases the tumor's growth rate.

Headaches may be present.

Diagnosis and workup

Diagnosis of pituitary adenoma can be made, or at least suspected, by a constellation of related symptoms presented above.

Tumors which cause visual difficulty are likely to be macroadenoma greater than 10 mm in diameter; tumors less than 10 mm are microadenoma.

The differential diagnosis includes pituitary tuberculoma, especially in developing countries and in immumocompromised patients. [8] The diagnosis is confirmed by testing hormone levels, and by radiographic imaging of the pituitary (for example, by CT scan or MRI).

Treatment

Treatment options depend on the type of tumor and on its size:

  • Prolactinomas are most often treated with bromocriptine or more recently, cabergoline or quinagolide which decrease tumor size as well as alleviates symptoms, both dopamine agonists, and followed by serial imaging to detect any increase in size. Treatment where the tumor is large can be with radiation therapy or surgery, and patients generally respond well. Efforts have been made to use a progesterone antagonist for the treatment of prolactinomas, but so far have not proved successful.
  • Somatotrophic adenomas respond to octreotide, a long-acting somatostatin analog, in many but not all cases according to a review of the medical literature. Unlike prolactinomas, thyrotrophic adenomas characteristically respond poorly to dopamine agonist treatment.[4]
  • Surgery is a common treatment for pituitary tumors. Trans-sphenoidal adenectomy surgery can often remove the tumor without affecting other parts of the brain. Endoscopic surgery has become common recently.[9]

Additional images

References

  1. ^ Ezzat S, Asa SL, Couldwell WT, Barr CE, Dodge WE, Vance ML, McCutcheon IE. (August 2004). "The prevalence of pituitary adenomas: a systematic review". Cancer 101 (3): 613–9. doi:10.1002/cncr.20412. PMID 15274075. 
  2. ^ Asa SL (August 2008). "Practical pituitary pathology: what does the pathologist need to know?". Arch. Pathol. Lab. Med. 132 (8): 1231–40. doi:10.1043/1543-2165(2008)132[1231:PPPWDT]2.0.CO;2. PMID 18684022. http://journals.allenpress.com/jrnlserv/?request=get-abstract&issn=0003-9985&volume=132&page=1231. Retrieved 2008-09-03. [dead link]
  3. ^ a b c d e page 526 in: Mandell, Brian F.; Stoller, James K.; Michota, Franklin A. (2009). The Cleveland Clinic Foundation intensive review of internal medicine. Hagerstwon, MD: Lippincott Williams & Wilkins. ISBN 0-7817-9079-4. 
  4. ^ a b Chanson P, Weintraub BD, Harris AG (August 1993). "Octreotide therapy for thyroid-stimulating hormone-secreting pituitary adenomas. A follow-up of 52 patients". Ann. Intern. Med. 119 (3): 236–40. PMID 8323093. http://www.annals.org/cgi/pmidlookup?view=long&pmid=8323093. Retrieved 2008-09-03. 
  5. ^ Ezzat S, Asa SL, Couldwell WT, et al. (August 2004). "The prevalence of pituitary adenomas". Cancer 101 (3): 613–9. doi:10.1002/cncr.20412. PMID 15274075. 
  6. ^ Alicja Furgal-Borzycha et al. (October 2007). "Increased Incidence of Pituitary Microadenomas in Suicide Victims". Neuropsychobiology 54 (3–4): 163–166. doi:10.1159/000106475. 
  7. ^ Forensic Neuropathology p. 137 By Jan E. Leestma
  8. ^ Saini KS, Patel AL, Shaikh WA, Magar LN, Pungaonkar SA (2007). "Magnetic resonance spectroscopy in pituitary tuberculoma". Singapore Med J 48 (8): 783–6. PMID 17657390. 
  9. ^ [1] American Cancer Society. "Detailed guide: Pituitary tumor. Surgery." Retrieved January 10, 2008

External links


Wikimedia Foundation. 2010.

Look at other dictionaries:

  • Pituitary adenoma — A benign tumor of the pituitary, the master gland that controls other glands and influences numerous body functions including growth. * * * a benign neoplasm of the anterior pituitary gland; some contain hormone secreting cells (functioning… …   Medical dictionary

  • Adenoma — Classification and external resources Micrograph of a tubular adenoma (left of image), a type of colonic polyp and a precursor of colorectal cancer. Normal colorectal mucosa is seen on the right of the image. H E stain …   Wikipedia

  • Pituitary gigantism — Excessive growth and too much height due to chronic overactivity of the pituitary gland which is located at the base of the brain. (Growth hormone is specifically made by the anterior pituitary gland.) In pituitary gigantism, there is secretion… …   Medical dictionary

  • Adenoma — A benign tumor that arises in or resembles glandular tissue. If it becomes cancerous, it is called an adenocarcinoma. * * * A benign epithelial neoplasm in which the tumor cells form glands or glandlike structures; usually well circumscribed,… …   Medical dictionary

  • adenoma — n. a benign tumour of epithelial origin that is derived from glandular tissue or exhibits clearly defined glandular structures. Adenomas may undergo malignant change (see adenocarcinoma). Some show recognizable tissue elements, such as fibrous… …   The new mediacal dictionary

  • Thyroid adenoma — Classification and external resources ICD 9 226 DiseasesDB 13071 …   Wikipedia

  • Anterior pituitary — Infobox Anatomy Name = PAGENAME Latin = lobus anterior hypophyseos GraySubject = 275 GrayPage = 1275 Caption = Median sagittal through the hypophysis of an adult monkey. Semidiagrammatic. Precursor = oral mucosa (Rathke s pouch) System = Artery …   Wikipedia

  • Combined rapid anterior pituitary evaluation panel — Diagnostics OPS 301 code 1 797 A triple bolus test or a dynamic pituitary function test is a medical diagnostic procedure used to assess a patient s pituitary function. A triple bolus test is usually ordered and interpreted by endocrinologists.… …   Wikipedia

  • gonadotrope adenoma — gonadotroph adenoma, gonadotroph cell adenoma a rare type of pituitary adenoma made up of gonadotroph like cells that secrete excessive amounts of follicle stimulating hormone or luteinizing hormone, or both; it may cause precocious puberty,… …   Medical dictionary

  • thyrotrope adenoma — thyrotroph adenoma, thyrotroph cell adenoma a rare type of pituitary adenoma made up of thyrotroph like cells that secrete excess thyrotropin and cause hyperthyroidism; called also TSH secreting a. and thyroid stimulating hormone–secreting a …   Medical dictionary


Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.