Pituitary adenomas are tumors that occur in the pituitary gland. Most pituitary tumors are benign, approximately 35% are invasive and just 0.1% to 0.2% are carcinomas.Pituitary Tumors Treatment (PDQ®)–Health Professional Version
NIH National Cancer Institute Pituitary adenomas represent from 10% to 25% of all intracranial neoplasms and the estimated

prevalence rate In epidemiology, prevalence is the proportion of a particular population found to be affected by a medical condition (typically a disease or a risk factor such as smoking or seatbelt use) at a specific time. It is derived by comparing the number o ...

in the general population is approximately 17%. Non-invasive and non-secreting pituitary adenomas are considered to be benign in the literal as well as the clinical sense; however a recent meta-analysis (Fernández-Balsells, ''et al.'' 2011) of available research has shown there are to date scant studies – of poor quality – to either support or refute this assumption. Adenomas exceeding in size are defined as ''macroadenomas'', with those smaller than referred to as ''microadenomas''. Most pituitary adenomas are microadenomas and have an estimated prevalence of 16.7% (14.4% in

autopsy An autopsy (post-mortem examination, obduction, necropsy, or autopsia cadaverum) is a surgical procedure that consists of a thorough examination of a corpse by dissection to determine the cause, mode, and manner of death or to evaluate any di ...

studies and 22.5% in radiologic studies). A majority of pituitary microadenomas often remain undiagnosed, and those that are diagnosed are often found as an ''

incidental finding Incidental medical findings are previously undiagnosed medical or psychiatric conditions that are discovered unintentionally and during evaluation for a medical or psychiatric condition. Such findings may occur in a variety of settings, including ro ...

'' and are referred to as '' incidentalomas''. Pituitary macroadenomas are the most common cause of hypopituitarism. While pituitary adenomas are common, affecting approximately one in 6 of the general population, clinically active pituitary adenomas that require surgical treatment are more rare, affecting approximately one in 1,000 of the general population.

Signs and symptoms

Physical

Hormone secreting pituitary adenomas cause one of several forms of

hyperpituitarism Hyperpituitarism is a condition due to the primary hypersecretion of pituitary hormones; it typically results from a pituitary adenoma. In children with hyperpituitarism, disruption of growth regulation is rare, either because of hormone hypersecr ...

. The specifics depend on the type of hormone. Some tumors secrete more than one hormone, the most common combination being GH and prolactin, which present as unexpected bone growth and unexpected lactation (in both men and women). A patient with pituitary adenoma may present with visual field defects, classically

bitemporal hemianopsia Bitemporal hemianopsia, is the medical description of a type of partial blindness where vision is missing in the outer half of both the right and left visual field. It is usually associated with lesions of the optic chiasm, the area where the opt ...

. 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

. 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 Lateral is a geometric term of location which may refer to: Healthcare *Lateral (anatomy), an anatomical direction *Lateral cricoarytenoid muscle *Lateral release (surgery), a surgical procedure on the side of a kneecap Phonetics *Lateral cons ...

palsy. Also, a pituitary adenoma can cause symptoms of increased intracranial pressure. Prolactinomas often start to give symptoms especially during pregnancy, when the increased hormone level estrogen can increase the tumor's growth rate. Various types of headaches are common in patients with pituitary adenomas. The adenoma may be the prime causative factor behind the headache or may serve to exacerbate a headache caused by other factors. Amongst the types of headaches experienced are both chronic and episodic

migraine Migraine (, ) is a common neurological disorder characterized by recurrent headaches. Typically, the associated headache affects one side of the head, is pulsating in nature, may be moderate to severe in intensity, and could last from a few hou ...

, and more uncommonly various unilateral headaches; primary stabbing headache, short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT) – another type of stabbing headache characterized by short stabs of pain – cluster headache, and hemicrania continua (HS). Compressive symptoms of pituitary adenomas (visual field deficits, decreased visual acuity, headaches) are more commonly seen with macroadenomas (which are greater than 10 mm in diameter) than with microadenomas (which are less than 10 mm in diameter). Non-secreting adenomas can go undetected for an extended time because no obvious abnormalities are seen; the gradual reduction in normal activities due to decreased production of hormones is rather less evident. For example, insufficient adrenocorticotropic hormone means that the adrenal glands will not produce sufficient

cortisol Cortisol is a steroid hormone, in the glucocorticoid class of hormones. When used as a medication, it is known as hydrocortisone. It is produced in many animals, mainly by the ''zona fasciculata'' of the adrenal cortex in the adrenal gland ...

, resulting in slow recovery from illness, inflammation, and chronic fatigue; insufficient growth hormone in children and adolescents leads to diminished stature but which can have many other explanations.

Psychiatric

Various psychiatric manifestations have been associated with pituitary disorders including pituitary adenomas. Psychiatric symptoms such as depression, anxiety apathy, emotional instability, easy irritability and hostility have been noted.

Complications

Acromegaly Acromegaly is a disorder that results from excess growth hormone (GH) after the growth plates have closed. The initial symptom is typically enlargement of the hands and feet. There may also be an enlargement of the forehead, jaw, and nose. Other ...

is a syndrome that results when the

anterior pituitary A major organ of the endocrine system, the anterior pituitary (also called the adenohypophysis or pars anterior) is the glandular, anterior lobe that together with the posterior lobe (posterior pituitary, or the neurohypophysis) makes up the p ...

gland produces excess growth hormone (GH). Approximately 90–95% of acromegaly cases are caused by a pituitary adenoma and it most commonly affects middle aged adults, Acromegly can result in severe disfigurement, serious complicating conditions, and premature death if unchecked. The disease which is often also associated with

gigantism Gigantism ( el, γίγας, ''gígas'', "giant", plural γίγαντες, ''gígantes''), also known as giantism, is a condition characterized by excessive growth and height significantly above average. In humans, this condition is caused by ove ...

, is difficult to diagnose in the early stages and is frequently missed for many years, until changes in external features, especially of the face, become noticeable with the median time from the development of initial symptoms to diagnosis being twelve years. * Cushing's syndrome is a hormonal disorder that causes hypercortisolism, which is elevated levels of

in the blood. Cushing's disease (CD) is the most frequent cause of Cushing's syndrome, responsible for approximately 70% of cases. CD results when a pituitary adenoma causes excessive secretion of adrenocorticotropic hormone (ACTH) that stimulates the adrenal glands to produce excessive amounts of

. :Cushing's disease may cause fatigue, weight gain, fatty deposits around the abdomen and lower back (truncal obesity) and face ("moon face"), stretch marks ( striae) on the skin of the abdomen, thighs, breasts, and arms,

hypertension Hypertension (HTN or HT), also known as high blood pressure (HBP), is a long-term medical condition in which the blood pressure in the arteries is persistently elevated. High blood pressure usually does not cause symptoms. Long-term high bl ...

glucose intolerance Prediabetes is a component of the metabolic syndrome and is characterized by elevated blood sugar levels that fall below the threshold to diagnose diabetes mellitus. It usually does not cause symptoms but people with prediabetes often have obesi ...

, and various infections. In women, it may cause excessive growth of facial hair ( hirsutism) and in men

erectile dysfunction Erectile dysfunction (ED), also called impotence, is the type of sexual dysfunction in which the penis fails to become or stay erect during sexual activity. It is the most common sexual problem in men.Cunningham GR, Rosen RC. Overview of male ...

. Psychiatric manifestations may include depression, anxiety, easy irritability, and emotional instability. It may also result in various

cognitive Cognition refers to "the mental action or process of acquiring knowledge and understanding through thought, experience, and the senses". It encompasses all aspects of intellectual functions and processes such as: perception, attention, thought, ...

difficulties. *

Hyperpituitarism Hyperpituitarism is a condition due to the primary hypersecretion of pituitary hormones; it typically results from a pituitary adenoma. In children with hyperpituitarism, disruption of growth regulation is rare, either because of hormone hypersecr ...

is a disease of the anterior lobe of the pituitary gland which is usually caused by a functional pituitary adenoma and results in hypersecretion of adenohypophyseal hormones such as growth hormone; prolactin; thyrotropin; luteinizing hormone; follicle-stimulating hormone; and adrenocorticotropic hormone. * Pituitary apoplexy is a condition that occurs when pituitary adenomas suddenly hemorrhage internally, causing a rapid increase in size or when the tumor outgrows its blood supply which causes tissue necrosis and subsequent swelling of the dead tissue. Pituitary apoplexy often presents with visual loss and sudden onset headache and requires timely treatment often with

corticosteroids Corticosteroids are a class of steroid hormones that are produced in the adrenal cortex of vertebrates, as well as the synthetic analogues of these hormones. Two main classes of corticosteroids, glucocorticoids and mineralocorticoids, are involve ...

and if necessary surgical intervention. * Central diabetes insipidus is caused by diminished production of the

antidiuretic hormone Human vasopressin, also called antidiuretic hormone (ADH), arginine vasopressin (AVP) or argipressin, is a hormone synthesized from the AVP gene as a peptide prohormone in neurons in the hypothalamus, and is converted to AVP. It then travel ...

vasopressin that causes severe thirst and excessive production of very dilute urine ( polyuria) which can lead to dehydration. Vasopressin is produced in the hypothalamus and is then transported down the pituitary stalk and stored in the posterior lobe of the pituitary gland which then secretes it into the bloodstream. As the pituitary gland is in close proximity to the brain, invasive adenomas may invade the dura mater, cranial bone, or

sphenoid bone The sphenoid bone is an unpaired bone of the neurocranium. It is situated in the middle of the skull towards the front, in front of the basilar part of occipital bone, basilar part of the occipital bone. The sphenoid bone is one of the seven bones ...

Risk factors

Multiple endocrine neoplasia

Adenomas of the anterior pituitary gland are a major clinical feature of multiple endocrine neoplasia type 1 (MEN1), a rare inherited endocrine syndrome that affects 1 person in every 30,000. MEN causes various combinations of benign or malignant tumors in various glands in the endocrine system or may cause the glands to become enlarged without forming tumors. It often affects the parathyroid glands, pancreatic islet cells, and anterior lobe of the pituitary gland. MEN1 may also cause non-endocrine tumors such as facial angiofibromas, collagenomas, lipomas, meningiomas, ependymomas, and

leiomyomas A leiomyoma, also known as a fibroid, is a benign smooth muscle tumor that very rarely becomes cancer (0.1%). They can occur in any organ, but the most common forms occur in the uterus, small bowel, and the esophagus. Polycythemia may occur due to ...

. Approximately 25 percent of patients with MEN1 develop pituitary adenomas.

Carney complex

Carney complex Carney complex and its subsets LAMB syndrome and NAME syndrome are autosomal dominant conditions comprising myxomas of the heart and skin, hyperpigmentation of the skin (lentiginosis), and endocrine overactivity. It is distinct from Carney's triad ...

(CNC), also known as LAMB syndrome and NAME syndrome is an

autosomal dominant In genetics, dominance is the phenomenon of one variant (allele) of a gene on a chromosome masking or overriding the effect of a different variant of the same gene on the other copy of the chromosome. The first variant is termed dominant and t ...

condition comprising

myxoma A myxoma (New Latin from Greek 'muxa' for mucus) is a myxoid tumor of primitive connective tissue. It is most commonly found in the heart (and is the most common primary tumor of the heart in adults) but can also occur in other locations. Ty ...

s of the heart and skin, hyperpigmentation of the skin ( lentiginosis), and

endocrine The endocrine system is a messenger system comprising feedback loops of the hormones released by internal glands of an organism directly into the circulatory system, regulating distant target organs. In vertebrates, the hypothalamus is the neu ...

overactivity and is distinct from Carney's triad. Approximately 7% of all cardiac myxomas are associated with Carney complex. Patients with CNC develop growth hormone (GH)-producing pituitary tumors and in some instances these same tumors also secrete prolactin. There are however no isolated prolactinomas or any other type of pituitary tumor. In some patients with CNC, the pituitary gland is characterized by hyperplastic areas with the hyperplasia most likely preceding the formation of GH-producing adenomas.

Familial isolated pituitary adenoma

Familial isolated pituitary adenoma (FIPA) is a term that is used to identify a condition that displays an

inheritance and is characterised by the presence of two or more related patients affected by adenomas of the pituitary gland only, with no other associated symptoms that occur in multiple endocrine neoplasia type 1 (MEN-1),

and with mutations in the aryl hydrocarbon receptor-interacting protein (AIP) gene. FIPA was first described in a limited cohort of families by Albert Beckers group in Liège, Belgium; later FIPA was fully characterized in a multicenter international study of 64 families. FIPA families are divided into those that are homogenous and have the same type of pituitary adenoma in all the affected family members (e.g. only

acromegaly Acromegaly is a disorder that results from excess growth hormone (GH) after the growth plates have closed. The initial symptom is typically enlargement of the hands and feet. There may also be an enlargement of the forehead, jaw, and nose. Other ...

, only prolactinoma, etc.), while heterogeneous FIPA families can have different pituitary adenomas in affected family members.

Genetics of FIPA

FIPA has two known genetic causes, mutations in the AH receptor-interacting protein (AIP) gene and duplications in chromosome Xq26.3 that include the ''

GPR101 Probable G-protein coupled receptor 101 is a protein that in humans is encoded by the ''GPR101'' gene. G protein-coupled receptors (GPCRs, or GPRs) contain 7 transmembrane domains and transduce extracellular signals through heterotrimeric G prote ...

'' gene that also causes X-linked acrogigantism (X-LAG) syndrome. About 15–20% of FIPA families carry a germline ''AIP'' gene mutation or deletion, and the disease occurs as autosomal dominant with incomplete penetrance, meaning that about 20% of AIP mutation carriers will develop a pituitary adenoma. ''AIP'' mutation associated pituitary adenomas (either presenting as FIPA or as individual, non familial cases) are usually growth hormone-secreting (

) or prolactin-secreting ( prolactinoma) adenomas that are large (macroadenomas) and often occur in children, adolescents and young adults. Daly and colleagues showed that acromegaly cases with ''AIP'' mutations occurred about 20 years before acromegaly cases without ''AIP'' mutations and these tumors are large and relatively treatment-resistant. Due to their young age at onset, ''AIP'' mutations are the most frequent genetic cause of

pituitary gigantism Gigantism ( el, γίγας, ''gígas'', "giant", plural γίγαντες, ''gígantes''), also known as giantism, is a condition characterized by excessive growth and height significantly above average. In humans, this condition is caused by ove ...

(29% of cases). X-LAG is a rare syndrome of very early childhood onset pituitary tumors/hyperplasia that leads to growth hormone excess and severe overgrowth and pituitary gigantism. Three FIPA families with X-LAG have been reported to date all of which had transmission of a chromosome Xq26.3 duplication from affected mother to affected son. The disease characteristics of very young onset

leads to severe overgrowth if not treated adequately; many of the tallest humans in history (e.g.

Robert Pershing Wadlow Robert Pershing Wadlow (February 22, 1918 July 15, 1940), also known as the Alton Giant and the Giant of Illinois, was an American man who was the tallest person in recorded history for whom there is irrefutable evidence. He was born and raise ...

;

Sandy Allen Sandra Elaine Allen (June 18, 1955 – August 13, 2008) was an American woman recognized by the Guinness World Records as the tallest woman in the world. She was tall. Allen wrote a book, ''Cast a Giant Shadow''. Although over the years other ...

, André Rousimoff (Andre the Giant), Zeng Jinlian) had a similar clinical history to patients with X-LAG syndrome. The tallest historical individual with a known genetic cause was Julius Koch (Geant Constantin) who was found to have X-LAG on genetic study of his skeleton. X-LAG has 100% penetrance so far (all affected with the Xq26.3 duplication have the disease and it affects predominantly females. Isolated non familial cases of X-LAG can either have a constitutional duplication of a chromosome Xq26.3 including ''

'', or mosaicism for the duplication (present in a minority of cells) in the case of isolated male patients. X-LAG causes about 10% of cases of

Mechanism

The pituitary gland or hypophysis is often referred to as the "master gland" of the human body. Part of the hypothalamic-pituitary axis, it controls most of the body's

functions via the secretion of various hormones into the circulatory system. The pituitary gland is located below the brain in a depression (

fossa Fossa may refer to: Animals * Fossa (animal), the common name of a carnivoran mammal of genus ''Cryptoprocta'' endemic to Madagascar * ''Fossa'', the Latin genus name of the Malagasy civet, a related but smaller mammal endemic to Madagascar Pla ...

) of the

known as the sella turcica. Although anatomically and functionally connected to the brain, the pituitary gland sits outside the

blood–brain barrier The blood–brain barrier (BBB) is a highly selective semipermeable membrane, semipermeable border of endothelium, endothelial cells that prevents solutes in the circulating blood from ''non-selectively'' crossing into the extracellular fluid of ...

. It is separated from the

subarachnoid space In anatomy, the meninges (, ''singular:'' meninx ( or ), ) are the three membranes that envelop the brain and spinal cord. In mammals, the meninges are the dura mater, the arachnoid mater, and the pia mater. Cerebrospinal fluid is located in th ...

by the diaphragma sella, therefore the

arachnoid mater The arachnoid mater (or simply arachnoid) is one of the three meninges, the protective membranes that cover the brain and spinal cord. It is so named because of its resemblance to a spider web. The arachnoid mater is a derivative of the neural c ...

and thus

cerebral spinal fluid Cerebrospinal fluid (CSF) is a clear, colorless body fluid found within the tissue that surrounds the brain and spinal cord of all vertebrates. CSF is produced by specialised ependymal cells in the choroid plexus of the ventricles of the bra ...

cannot enter the sella turcica. The pituitary gland is divided into two lobes, the anterior lobe (which accounts for two thirds of the volume of the gland), and the posterior lobe (one third of the volume) separated by the

pars intermedia Pars intermedia is the boundary between the anterior and posterior lobes of the pituitary. It contains colloid-filled cysts and two types of cells - basophils and chromophobes. The cysts are the remainder of Rathke’s pouch. In human fetal life ...

. The

posterior lobe The cerebellum (Latin for "little brain") is a major feature of the hindbrain of all vertebrates. Although usually smaller than the cerebrum, in some animals such as the mormyrid fishes it may be as large as or even larger. In humans, the cerebe ...

(the neural lobe or neurohypophysis) of the pituitary gland is not, despite its name, a true

gland In animals, a gland is a group of cells in an animal's body that synthesizes substances (such as hormones) for release into the bloodstream (endocrine gland) or into cavities inside the body or its outer surface (exocrine gland). Structure De ...

. The posterior lobe contains

axons An axon (from Greek ἄξων ''áxōn'', axis), or nerve fiber (or nerve fibre: see American and British English spelling differences#-re, -er, spelling differences), is a long, slender projection of a nerve cell, or neuron, in vertebrates, th ...

neurons A neuron, neurone, or nerve cell is an electrically excitable cell that communicates with other cells via specialized connections called synapses. The neuron is the main component of nervous tissue in all animals except sponges and placozoa. N ...

that extend from the hypothalamus to which it is connected via the pituitary stalk. The hormones vasopressin and

oxytocin Oxytocin (Oxt or OT) is a peptide hormone and neuropeptide normally produced in the hypothalamus and released by the posterior pituitary. It plays a role in social bonding, reproduction, childbirth, and the period after childbirth. Oxytocin ...

, produced by the neurons of the supraoptic and

paraventricular nuclei The paraventricular nucleus (PVN, PVA, or PVH) is a nucleus in the hypothalamus. Anatomically, it is adjacent to the third ventricle and many of its neurons project to the posterior pituitary. These projecting neurons secrete oxytocin and a smaller ...

of the hypothalamus, are stored in the posterior lobe and released from axon endings ( dendrites) within the lobe. The pituitary gland's

anterior lobe The anterior lobe of cerebellum is the portion of the cerebellum responsible for mediating unconscious proprioception. Inputs into the anterior lobe of the cerebellum are mainly from the spinal cord. It is sometimes equated to the "paleocerebellu ...

(adenohypophysis) is a true gland which produces and secretes six different hormones: thyroid-stimulating hormone (TSH), adrenocorticotropic hormone (ACTH),

follicle-stimulating hormone Follicle-stimulating hormone (FSH) is a gonadotropin, a glycoprotein polypeptide hormone. FSH is synthesized and secreted by the gonadotropic cells of the anterior pituitary gland and regulates the development, growth, pubertal maturation, an ...

(FSH), luteinizing hormone (LH), growth hormone (GH), and prolactin (PRL).

Diagnosis

Diagnosis of pituitary adenoma can be made, or at least suspected, by a constellation of related symptoms presented above. The differential diagnosis includes pituitary tuberculoma, especially in developing countries and in immumocompromised patients. The diagnosis is confirmed by testing hormone levels, and by radiographic imaging of the pituitary (for example, by

CT scan A computed tomography scan (CT scan; formerly called computed axial tomography scan or CAT scan) is a medical imaging technique used to obtain detailed internal images of the body. The personnel that perform CT scans are called radiographers ...

or MRI).

Classification

Unlike tumors of the posterior Pituitary, Pituitary adenomas are classified as endocrine tumors (not brain tumors). Pituitary adenomas are classified based upon

anatomical Anatomy () is the branch of biology concerned with the study of the structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old science, having it ...

, histological and functional criteria. * Anatomically pituitary tumors are classified by their size based on radiological findings; either microadenomas (less than <10 mm) or macroadenomas (equal or greater than ≥10 mm). :Classification based on radioanatomical findings places adenomas into 1 of 4 grades (I–IV): :Stage I: microadenomas (<1 cm) without sella expansion. :Stage II: macroadenomas (≥1 cm) and may extend above the sella. :Stage III: macroadenomas with enlargement and invasion of the floor or suprasellar extension. :Stage IV: destruction of the sella. * Histological classification utilizes an immunohistological characterization of the tumors in terms of their hormone production. Historically they were classed as either basophilic,

acidophilic Acidophiles or acidophilic organisms are those that thrive under highly acidic conditions (usually at pH 5.0 or below). These organisms can be found in different branches of the tree of life, including Archaea, Bacteria,Becker, A.Types of Bacteria ...

, or

chromophobic A chromophobe is a histological structure that does not stain readily, and thus appears relatively pale under the microscope. Chromophobe cells are one of three cell stain types present in the anterior and intermediate lobes of the pituitary gland ...

on the basis of whether or not they took up the

tinctorial A tincture is typically an extract of plant or animal material dissolved in ethanol (ethyl alcohol). Solvent concentrations of 25–60% are common, but may run as high as 90%.Groot Handboek Geneeskrachtige Planten by Geert Verhelst In chemistr ...

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. Approximately 20–25% of adenomas do not secrete any readily identifiable active hormones ('non-functioning tumors') yet they are still sometimes referred to as 'chromophobic'. * Functional classification is based upon the tumors endocrine activity as determined by

serum Serum may refer to: *Serum (blood), plasma from which the clotting proteins have been removed **Antiserum, blood serum with specific antibodies for passive immunity * Serous fluid, any clear bodily fluid * Truth serum, a drug that is likely to mak ...

hormone levels and pituitary tissue cellular hormone secretion detected via immunohistochemical staining. 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, non secretive adenomas may be either ''null cell adenomas'' or a more specific adenoma that, however, remains non-secretive. * Any type of pituitary adenocarcinoma listed in the table below may cause compressive symptoms due to local expansion in addition to the systemic effects of secreted hormones listed in the pathology column. * Null cell adenomas by definition do not secrete hormones, but they commonly cause compressive effects on the pituitary stalk (stalk effect). This leads to decreased levels of

dopamine Dopamine (DA, a contraction of 3,4-dihydroxyphenethylamine) is a neuromodulatory molecule that plays several important roles in cells. It is an organic compound, organic chemical of the catecholamine and phenethylamine families. Dopamine const ...

from the hypothalamus reaching the anterior pituitary gland. Dopamine exerts an inhibitory effect on prolactin secretion. With the absence of this inhibitory effect, prolactin levels increase and are often increased in null cell adenomas. This leads to symptoms of hypogonadism. File:Pituitary adenoma (2) GH production.jpg, Somatotroph pituitary adenoma, showing acidophilic cytoplasm File:Histopathology of eosinophilic silent gonadotroph pituitary adenoma.jpg, A silent gonadotroph pituitary adenoma which is, in this case, eosinophilic (contrary to normal, basophilic, gonadotroph cells) File:Histopathology of a true null cell adenoma.jpg, True null cell adenomas are typically composed of uniform, mildly atypical cells with chromophobic cytoplasm. This case has papillary architecture similar to gonadotroph adenomas.

Pituitary incidentalomas

Pituitary incidentalomas are pituitary tumors that are characterized as an

. They are often discovered by

computed tomography A computed tomography scan (CT scan; formerly called computed axial tomography scan or CAT scan) is a medical imaging technique used to obtain detailed internal images of the body. The personnel that perform CT scans are called radiographers ...

(CT) or

magnetic resonance imaging Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to form pictures of the anatomy and the physiological processes of the body. MRI scanners use strong magnetic fields, magnetic field gradients, and radio wave ...

(MRI), performed in the evaluation of unrelated medical conditions such as suspected head trauma, in cancer staging or in the evaluation of nonspecific symptoms such as dizziness and

headache Headache is the symptom of pain in the face, head, or neck. It can occur as a migraine, tension-type headache, or cluster headache. There is an increased risk of depression in those with severe headaches. Headaches can occur as a result ...

. It is not uncommon for them to be discovered at

. 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. While non-secreting, noninvasive pituitary microadenomas are generally considered to be literally as well as clinically benign, there are to date scant studies of low quality to support this assertion. It has been recommended in the current Clinical Practice Guidelines (2011) by the

Endocrine Society The Endocrine Society is a professional, international medical organization in the field of endocrinology and metabolism, founded in 1916 as The Association for the Study of Internal Secretions. The official name of the organization was changed ...

– a professional, international medical organization in the field of endocrinology and metabolism – that all patients with pituitary incidentalomas undergo a complete medical history and physical examination, laboratory evaluations to screen for hormone hypersecretion and for hypopituitarism. If the lesion is in close proximity to the optic nerves or optic chiasm, a visual field examination should be performed. For those with incidentalomas which do not require surgical removal, follow up clinical assessments and neuroimaging should be performed as well follow-up visual field examinations for incidentalomas that abut or compress the optic nerve and chiasm and follow-up endocrine testing for macroincidentalomas.

Ectopic pituitary adenoma

An ectopic (occurring in an abnormal place) pituitary adenoma is a rare type of tumor which occurs outside of the sella turcica, most often in the sphenoid sinus, suprasellar region, nasopharynx and the cavernous sinuses.

Metastases to the pituitary gland

Carcinomas that metastasize into the pituitary gland are uncommon and typically seen in the elderly, with

lung The lungs are the primary organs of the respiratory system in humans and most other animals, including some snails and a small number of fish. In mammals and most other vertebrates, two lungs are located near the backbone on either side of t ...

and breast cancers being the most prevalent, In breast cancer patients, metastases to the pituitary gland occur in approximately 6–8% of cases. Symptomatic pituitary metastases account for only 7% of reported cases. In those who are symptomatic diabetes insipidus often occurs, with rates approximately 29–71%. Other commonly reported symptoms include anterior pituitary dysfunction, visual field defects, headache/pain, and ophthalmoplegia.

Treatment

Treatment options depend on the type of tumor and on its size: * Prolactinomas are most often treated with cabergoline or bromocriptine (both dopamine agonists), which decrease tumor size as well as alleviates symptoms, followed by serial imaging to detect any increase in size. Treatment, where the tumor is large, can be with radiation therapy, proton therapy or surgery, and patients generally respond well. Unlike prolactinomas, thyrotrophic adenomas characteristically respond poorly to dopamine agonist treatment. * Somatotrophic adenomas respond to octreotide or lanreotide, which are long-acting

somatostatin Somatostatin, also known as growth hormone-inhibiting hormone (GHIH) or by several other names, is a peptide hormone that regulates the endocrine system and affects neurotransmission and cell proliferation via interaction with G protein-couple ...

analogs. These somatostatin receptor analogs inhibit secretion of growth hormone. They were found to be about 50–55% effective in reducing tumor mass and reducing growth hormone and insulin like growth factor 1 (

IGF-1 Insulin-like growth factor 1 (IGF-1), also called somatomedin C, is a hormone similar in molecular structure to insulin which plays an important role in childhood growth, and has anabolic effects in adults. IGF-1 is a protein that in humans is ...

) levels in studies. The growth hormone receptor antagonist

pegvisomant Pegvisomant, sold under the brand name Somavert, is a growth hormone receptor antagonist used in the treatment of acromegaly. It is primarily used if the pituitary gland tumor causing the acromegaly cannot be controlled with surgery or radiatio ...

is also used in the treatment of somatotrophic adenomas. Pegvisomant blocks the action of growth hormone. It can either be used as monotherapy or combined with a somatostatin analog. * Surgery is a common treatment for pituitary tumors. The normal approach is trans-sphenoidal adenectomy, which usually can remove the tumor without affecting the brain or optic nerves.Transsphenoidal Surgery FAQ
Neuroendocrine Clinical Center, Massachusetts General Hospital/Harvard Medical School. Retrieved November 25, 2016 * Radiation is also used to treat pituitary adenomas. Examples include external beam or proton beam radiation therapy or stereotactic radiosurgery. External radiation of pituitary adenomas can arrest tumor growth for several years but pituitary failure develops within 10 years in most patients necessitating lifelong hormone replacement. Radiation therapy for pituitary adenomas is associated with a four-fold increase in mortality due to cerebrovascular disease.

References

External links

Cancer.gov: pituitary tumors
{{DEFAULTSORT:Pituitary Adenoma Endocrine neoplasia Neuroendocrinology