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75 Cards in this Set

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  • Back
What is the normal location of the Pituitary Gland?
within the Sella Turcica, a concavity of the Sphenoid Bone, whoch forms part of the base of the skull
Which part of the Pituitary is the "producer"? "Storehouse"?
Producer = Anterior

Storehouse = Posterior
What part of the Pituitary is connected to the Infundibulum (Median Eminence) via a stalk?
Posterior Pituitary
Explain why the Posterior Lobe is considered a "storehouse"
Hormones are made in the Hypothalamus & travel down to the Posterior Pituitary via axons & are stored until released
Describe the circulation of the Posterior Lobe
receives circulation via an Artery & has direct release of hormones into a Vein
Describe the circulation of the Anterior Pituitary
receives blood from the Portal Venous System
If blood supply to the Pituitary is compromised, which lobe gets hit the hardest? Why?
Anterior b/c it receives venous blood
What anatomical structures are in proximity to the Pituitary?
1. Optic Chiasm
2. Hypothalamus
3. Internal Carotid Arteries (Cavernous Sinus)
4. Sphenoid Sinus
What happens if the Pituitary compresses the central portion of the optic chiasm?
Bitemporal Hemianopsia
What may happen if a Pituitary Tumor compresses the 3rd Ventricle?
What may happen if a Pituitary Tumor compresses the Cavernous Sinus?
Internal Carotid Artery compression
What is the embryological origin of the Anterior Lobe?
Oral Ectoderm (Stomodeum) -> Rathke's Pouch -> Anterior lobe
What is the embryological origin of the Posterior Lobe?
Neuroectoderm (Diencephalon)
During what embryological time period does the Pituitary begin to form?
3-8 weeks
Describe the embryological formation of the Pituitary
At about 3-5 weeks, Rathke's Pouch buds upwards into the cranial cavity

At the same time Neuroectoderm is coming down from the floor of the Diencephalon (developing Hypothalamus) to meet the tissue of Rathke's Pouch
From what Hypothalamic nucleus is Vasopressin (ADH) synthesized?

ADH = Supraoptic

Oxytocin = Paraventricular
List the 7 hormones released from the Anterior Pituitary & also name the stimulators for each
1. TSH <- TRH
2. LH <- GnRH, Estrogen
3. FSH <- GnRH, Estrogen
4. ACTH <- CRF
5. MSH <- CRF
6. GH <- GHRH
7. Prolactin <- TRH
What does the histology of the Posterior Pituitary contain?
1. Glia = Pituicytes

2. Axons from Hypothalamus (Herring bodies = nerve terminals from which ADH & Oxytocin are released)
What are the 5 cell types in the Anterior Lobe?
1. Somatotrophs GH
2. Lactotrophs = Prolactin
3. Corticotrophs = ACTH, POMC, MSH
4. Thyrotrophs = TSH
5. Gonadotrophs = FSH & LH
T or F: The majority of Pituitary tumors are associated with the MEN type 1 symdrome
False = most are sporadic
What is the most common tumor type of the Pituitary?
Adenoma = benign & most are composed of a single cell type & secrete only 1 hormone
What is the gross pathology associated with Pituitary Adenomas?
1. Soft, well circumscribed
2. possible compression of adjacent structures
3. possible local invasion
4. Pituitary Apoplexy = bleeding within the gland
What is the microscopic pathology seen in Pituitary Adenomas?
1. Sheets of Monotonous cells

2. sparse intervening Connective Tissue
What is the #1 type of Hyperfunctioning Pituitary Adenoma & accounts for 30% of Adenomas?
What are the main clinical features of Prolactinomas?
Female of reproductive age = Amenorrhea & Galactorrhea

Men = loss of libido & infertility
Why do Prolactinomas cause Amenorrhea in women?
Prolactin inhibits GnRH release -> decreased LH & FSH
In what people are Prolactinoma's more easily diagnosed?
women age 20-40
What are the lab findings associated with Prolactinoma's
1. increased Prolactin

2. decreased FSH & LH due to feedback inhibition by Prolactin on GnRH
In what people are Prolactinoma's usually larger?
Older age = post-menopausal women don't notice amenorrhea
What is the treatment for Prolactinoma's?
Bromocriptine & Cabergoline = Dopamine agonists

**Dopamine from Hypothalamus inhibits Prolactin secretion from Anterior Pituitary
2nd most common Pituitary Adenoma with Hyperfunction
Growth Hormone Adenoma
What gene do 40% of Growth Hormone Adenoma's express?
gsp oncogene (GTPase deficiency)
What is the treatment for Growth Hormone Adenomas?
Octreotide = mimics Somatostatin to inhibit GH secretion
What are the clinical manifestations of Growth Hormone Adenoma's?
1. Children = gigantism

2. Adults = Acromegaly
What are 2 pharmacologic agents that interfere with Dopamine secretion & could mimic a Prolactinoma?
Methyl-dopa = increased alpha-2 receptor-mediated inhibition of SNS

Reserpine = blocks the storage of NE & Dopamine in secretory vesicles
What are the clinical features of Gigantism?
Tall stature & long extremities due to the fact that Epiphyseal Plates have not closed yet
What are the clinical features of Acromegaly?
-Prominent Jaw
-Flat, broad forehead
-Enlarged hands & feet

**Epiphyseal plates have closed = increased LATERAL bone growth but not linear
What are associated findings in Growth Hormone Adenoma's?
1. Diabetes Mellitus = GH stimulates gluconeogenesis
2. Muscle weakness
3. Hypertension
4. Congestive Heart Failure
5. Organomegaly
What do Corticotroph Adenoma's cause?
Cushing Disease due to excess ACTH secretion resulting in Hypercortisolism
Describe Nelson Syndrome
-Bilateral adrenalectomy causes enlargement of a preexisting Pituitary Adenoma due to lack of Cortisol negative feedback on ACTH

-Hyperpigmentation due to MSH excess
Name for nonfunctional Adenomas but may cause mass effects
Null Cell Adenoma
How do Gonadotroph Adenoma's present clinically?
Usually do NOT produce distinct clinical syndromes & are usually diagnosed only after they have attained a size that will cause a mass effect

Menstrual abnormalities, infertility & various nonspecific hormonal changes are found in some patients
Discuss Pituitary Carcinoma's
-requires demonstration of metastases to distant sites = lymph nodes, bone, liver
What percent of the Pituitary has to be lost before Hypopituitarism is encountered?
75% loss
What are 3 etiologies of Hypopituitarism?
1. tumors

2. ischemic necrosis

3. Empty Sella Syndrome
Discuss a Rathke Cleft Cyst
Benign cyst that forms in the stalk or Anterior Lobe
- as it enlarges it can compress the normal gland & lead to hypopituitarism
List 4 Sellar Tumors that may cause Hypopituitarism
1. Adenomas
2. Carcinomas
3. Metastases
4. Rathke Cleft Cyst
List 3 Suprasellar tumors that may cause Hypopituitarism
1. Gliomas
2. Germinomas
3. Craniopharyngiomas
Most common intracranial germ cell tumor
1. What is the location of Germinoma's?

2. What is the histology of Germinoma's?

3. Who are most often affected?

4. What lab findings are associated?
1. Midline, suprasellar, or pineal

2. Germ cells + T cells

3. Japanese men

What is a Craniopharyngioma?
Benign pituitary tumor derived from Rathke's Pouch remnants
What is the most common cause of Hypopituitarism in children?
How are Craniopharyngiomas manifested in children? Adults?
Children = endocrine abnormalities

Adults = visual abnormalities
What are the 2 histological variants of Craniopharyngioma?
1. Adamantinomatous

2. Papillary
Describe the histology of Adamantinomatous Craniopharyngioma's
-Stratified squamous epithelium
-Wet keratin
-Cholesterol-rich fluid cyst ("motor oil")
-Chronic inflammation
-fingers extend into adjacent brain
Describe Sheehan Syndrome
Postpartum Pituitary Necrosis
-massive blood loss at time of delivery causes hypoperfusion of the pituitary that has undergone physiological hyperplasia during pregnancy
What conditions could cause Ichemic Necrosis of the Pituitary resulting in Hypopituitarism?
1. DIC
2. Sicke cell anemia
3. trauma
4. shock of any origin
What is the pathology seen in Ischemic necrosis of the Pituitary?
Grossly atrophic = <0.1 gm

Fibrous Scar tissue
What is the most common cause of Empty Sella Syndrome?
Diaphragmatic hernia
Describe Primary Empty Sella Syndrome
Pituitary atrophy is related to a compression by the CSF & Arachnoidea that invaginate into the Sella through a defect in the diaphragm
What are 3 "other" causes of Empty Sella Syndrome?
1. Sheehan's syndrome
2. Infarction of adenoma
3. Sellar mass treated by surgery/radiation
Describe the mnemonic for the most common causes of Hypopituitarism
Invasion by tumors
Injury = head trauma
Infarction = postpartum Sheehan syndrome
Immune diseases = Sarcoidosis; Autoimmune Hypophysitis
Infection = basal meningitis, TB
Inborn errors of metabolism
What congenital defect causes Hypopituitarism from patients not being able to make pituitary hormones?
defect in Transcription Factor Pit-1 gene
-defective protein binds DNA but does not activate target genes
Invasive Pituitary Adenoma
-patient had 2-year history of dementia & visual impairment
What is seen here?
Pituitary Adenoma
What is seen here?
Pituitary Adenoma
What is seen here?
Rathke Cleft Cyst = benign cyst that forms in the stalk or Anterior lobe
What is seen here?
Germinoma = suprasellar tumor
What is seen here?
Craniopharyngioma = mass of cysts & solid areas
What is seen here?
Adamantinomatous Craniopharyngioma
What is seen here?
Papillary Craniopharyngioma
What is seen here?
Empty Sella Syndrome, primary type
What is seen here?
Pituitary Apoplexy
What is seen here?