Chapter 24- Pituitary Flashcards
What are the specific symptoms commonly seen with a mass effect of pituitary lesions
- Bilateral temporal hemianopsia (compression of the nasal portion of the optic chiasm)
- Pituitary apoplexy (hemorrhage into adenoma)
- Underproduction of pituitary hormones
- Hyperprolactinemia
Which cells can be intermixed with somatotroph adenomas
Prolactin secreting cells
What are the treatments for a corticotroph adenoma
Somatostatin or dopamine agonists
*Express dopamine and somatostatin receptors
What is the released from the hypothalamus onto the pituitary for the release of TSH
Thyroid releasing hormone (TRH)
USP8 mutations are most commonly seen in which pituitary adenomas
Sporadic Corticotroph adenomas
*Results in EGFR up regulations
What is the released from the hypothalamus onto the pituitary for the release of prolactin
Dopamine
What are the causes for Cushing syndrome if there is high ACTH
ACTH dependent:
- Pituitary tumor (Cushing Disease)
- Ectopic ACTH producing tumor
How does the posterior pituitary receive regulatory hormones
Direct stimulation and release from the hypothalamus
How does a nonfunctioning pituitary adenoma usually get found
Mass effect
What are the hormones released from the posterior pituitary
ADH and oxytocin
What is the result of the hypothalamus releasing GHRH
Increased GH released
What is the result of a craniopharyngioma in kids 5-15 years of age
Adamatntinomatous craniopharyngiomas, which is hardening of the bone there
-Results in Growth retardation from hypopharnygiomas
What are the characteristics of pituitary carcinomas
- Very rare
- Metastasized to brain
What are the complications seen with a Rathke’s cleft cyst
- Hypopituitarism
- Rupture leading to inflammation of meninges and pituitary
What are the conditions that can cause hyperprolactinemia
- Pregnancy
- nipple/lactation stimulation
- Loss of dopamine
- Mass lesion
- Renal failure (decreased production and decreased clearance of PRL)
- Hypothyroidism (increased TSH can stimulate PRL)
How does the anterior pituitary receive input via regulatory hormones
-Released from the hypothalamus into the hypophyseal portal system to reach that anterior pituitary
What is the most common cause of cushing syndome
Glucocorticoids
What is the tissue origin of the anterior pituitary
Oral ectoderm
What is the most common secretory pituitary adenoma
Lactotroph adenoma (aka prolactinoma)
*30%
What is the released from the hypothalamus onto the pituitary for the release of FSH
Gonadotropin releasing hormone
What are the general symptoms of mass effect of pituitary lesions
Result of increased intracranial pressure: Headache Confusion Shallow breathing Nausea
What is the method used to establish a diagnosis of somatotroph adenoma
1) Serum levels of IGF-1 are measured looking for elevations
2) If IGF-1 is elevated, then perform a oral glucose tolerance test. If remains elevated, then positive
What conditions are caused by somatotroph adenoma
Gigantism and acromegaly
What is cushing’s disease
Caused by excess pituitary ACTH
*usually a corticotroph adenoma
What is empty sell syndrome
Hypopituitarism condition:
-CSF builds up and compresses the pituitary
What is the common neoplasm causing cushing syndrome
Small cell carcinoma of the lung
What are the findings in lactotroph adenomas as they progress
- Stromal hyalinization with psommoma bodies
- Dense calcification in the form of a pituitary stone
What is the released from the hypothalamus onto the pituitary for the release of growth hormone
Growth hormone releasing hormone
What is the histological finding in the anterior lobe
Glands, so forms adenohypophysis
What is the result of the hypothalamus releasing TRH
Increased TSH release
What is the released from the hypothalamus onto the pituitary for the release of ACTH
Corticotroph releasing hormone (CRH)
What is the negative regulator for TSH release on both the hypothalamus and pituitary
T3/T4
What is the hormone released with somatotroph adenomas
Growth hormones
What is Cushing syndrome
- Central obesity
- Diabetes
- Hirsutism (hair on face/cheeks)
- Adrenal hyperplasia
*All stemming from hypercortisolism
What is the typical presentation of lactotroph adenomas (prolactinoma) in women
- Menstral irregulations and amenorrhea
- Galactorrhea
- Diminished libido
- Infertility
- Mass effect
What type of cell releases growth hormone
Somatotroph
What is the result of the hypothalamus releasing somatostatin
Inhibition on GH
What is the primary cause if empty sella syndome
Diaphragma seller does not form, allowing CSF to leak in and compress the pituitary
- Most commonly seen in obese women with a history of multiple pregnancies
The posterior pituitary is from what tissue origin
Brain, so neuroectoderm
What classification of lactotroph adenomas are most common
Sparsely granulated
What is the relative lifespan of a patient with acromegaly and what is the cause
Shortened lifespan, usually due to cardiovascular complications
What is the significance of receptors expressed by corticotroph adenomas with regards to treatment
-Dopamine and somatostatin receptors are expressed, so analogs can be used in treatment as they inhibit ACTH production
How are gonadotropin adenomas normally found
Mass effect and are typically silent adenomas
What is a craniopharyngioma
Tumor leading to hypopituitarism
Why is the anterior pituitary susceptible in the cause of Sheehan syndome
Mostly dependant on venous blood supply, so sensitive to compression
What type of cell releases prolactin
Lactotroph
What is the negative regulator on only the hypothalamus with release of ACTH
CRH
What is the purpose of a dexamethasone suppression test
High lively os dexamethasone sed in the case of ACTH dependent Cushing syndrome:
- Pituitary tumor will decreased ACTH production slightly during test (retains some negative feedback loop)
- Ectopic ACTH tumor will not change ACTH production (such as in small cell carcinoma)
What is the result of a craniopharyngioma in adults >65 years of age
- Papillary craniopharyngioma
- Causes increased incracranial pressure and hypopituitarism
What si the histological finding of a Rathke’s cleft cyst
-Ciliated, as it is derived from the oropharynx
What is the imaging done for an ACTH independent Cushing syndrome
Abdominal CAT scan/MRI
How does a hyperfunctioning adenoma usually get found
Hormone excess
What are the histological components of craniopharyngiomas
- Derived from Rathke’s pouch
- Squamous epithelium
- “wet” keratin
- Calcified cysts
Which drugs can cause hyperprolactinemia and what is the mechanism
Blocks dopamine release:
- Antiphyschotics,
- antidepressants
- Verapamil
- Metoclopramide
What type of cell releases TSH
Thyrotroph
What is the product being released during a corticotroph adenoma
ACTH and subsequent cortisol release
What is Rathke’s cleft cyst
Hypopituitarism condition :
-Cystic mass derived from Rathke’s pouch expands and compresses the pituitary
What is the purpose and mechanism of an oral glucose test
used to test for somatotroph adenomas:
- Oral glucose causes increased somatostatin levels
- Somatostatins inhibit the release of GH and subsequent IGF-1
What is the result of the hypothalamus releasing CRH
Increased ACTH release
How will Sheehan syndome usually present
Lack of lactation
What is the presentation of lactotroph adenoma (prolactinoma) in males
Decreased libido
Decreased sperm count
Mass effect*
*Most common findings since the other effects are not usually enough to be seen
What are the systemic conditions that can cause hyperprolactinemia
- Renal failure
- Hypothyroidism
What is the treatment of prolactin pituitary adenomas
Dopamine Agonists
What is occurring in secondary empty sella syndrome
Pituitary expands and infarcts within the sella, leaving and empty space for the CSF to build up and compress the pituitary
What is the blood serum state in the cause of SIADH
Hyponatremia due to water retention
What is the mechanism that mutations in GNAS results in pituitary adenomas
Mutation allows the alpha subunit to lose its GTPase activity , so GTP remains bound and cAMP derived proliferation occurs
What is the released from the hypothalamus onto the pituitary for the release of LH
Gonadotropin releasing hormone
What are the causes for Cushing syndrome if there is low ACTH
Adrenal caused Cushing Syndrome (ACTH independent):
- Adrenal adenoma or carcinoma
- Bilateral adrenal hyperplasia
GNAS mutations are most commonly seen in which pituitary adenomas
Somatic somatotroph adenomas
What is Nelson syndrome
Occurs when the adrenal glands are removed or missing:
- Increased ACTH levels to try to elevate cortisol levels
- As a result of elevated ACTH, skin pigmentation will increase, as well symptoms similar to pituitary tumor due to hyperplasia (such as visual defects)
What is the structure formed from Rathke’s pouch
Anterior pituitary
What are the characteristics of aggressive pituitary adenomas
- Poorly circumscribed
- Can invade the brain
- More likely in larger adenomas
What is a cause of SIADH
- Small cell carcinoma of the lung
- Traumatic brain injury/subarachnoid hemorrhage
- Drugs (SSRIs)
What is the negative regulator for LH release on both the hypothalamus and pituitary
Testosterone
Inhibin
Estradiol
Progesterone
What type of cell releases LH
Gonadotropin
What is the most common cause of hyperpituitism
Adenoma of the anterior lobe
What is the result of the hypothalamus releasing GnRH
FSH
LH
AIP is most commonly seen in which pituitary adenomas
Familial somatotroph adenomas aka familial gigantism
What is the negative regulator for ACTH release on both the hypothalamus and pituitary
Cortisol
What is the imaging done for ACTH dependent caused Cushing syndrome
MRI of brain
Petrosky sinus sampling
What is the result of the hypothalamus releasing dopamine
Inhibition of prolactin
What type of cell releases ACTH
Corticotroph
What is the treatment for somatotroph adenomas
Somatostatin agonist inhibits GH release
What is Sheehan syndrome
Hypopituitarism condition:
-Post partum necrosis of the anterior pituitary (pregnancy causes enlargement of pituitary gland, so much that in some cases can cause necrosis)
What is the negative regulator for GH release on both the hypothalamus and pituitary
IGF
What are the histological characteristics of a somatotroph adenomas
-Diffuse growth and made with using a GH immunostain
What determines if a patient with somatotroph adenomas will develop gigantism or acromegaly
Depends on whether the growth plates have sealed or not.
- Gigantism: growth plates have not sealed and long bones grow
- Acromegaly: growth plates have sealed and features become more course
What is the histological findings of the posterior lobe
Neuro tissue
What are the physical features of acromegaly
- Enlarged face and hands
- Protruding jaw
- Enlarged nose
- Thickened lips
- Joint point
- Enlarged viscera
What are the characteristics of pituitary adenomas
- Well circumscribed
- Can erode bone
- Can bleed
What type of cell releases FSH
Gonadotroph
What is the purpose of a corticotroph releasing hormone (CRH) stimulation test
Used in the cause ACTH dependent cushing syndome:
- Corticotroph adenomas will remain responsive to CRH and increase ACTH production
- Ectopic will not be responsible to CRH