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75 Cards in this Set
- Front
- Back
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What is the normal location of the Pituitary Gland?
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within the Sella Turcica, a concavity of the Sphenoid Bone, whoch forms part of the base of the skull
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Which part of the Pituitary is the "producer"? "Storehouse"?
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Producer = Anterior
Storehouse = Posterior |
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Label
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-
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Label
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-
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What part of the Pituitary is connected to the Infundibulum (Median Eminence) via a stalk?
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Posterior Pituitary
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Explain why the Posterior Lobe is considered a "storehouse"
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Hormones are made in the Hypothalamus & travel down to the Posterior Pituitary via axons & are stored until released
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Describe the circulation of the Posterior Lobe
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receives circulation via an Artery & has direct release of hormones into a Vein
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Describe the circulation of the Anterior Pituitary
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receives blood from the Portal Venous System
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If blood supply to the Pituitary is compromised, which lobe gets hit the hardest? Why?
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Anterior b/c it receives venous blood
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What anatomical structures are in proximity to the Pituitary?
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1. Optic Chiasm
2. Hypothalamus 3. Internal Carotid Arteries (Cavernous Sinus) 4. Sphenoid Sinus |
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What happens if the Pituitary compresses the central portion of the optic chiasm?
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Bitemporal Hemianopsia
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What may happen if a Pituitary Tumor compresses the 3rd Ventricle?
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Hydrocephalus
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What may happen if a Pituitary Tumor compresses the Cavernous Sinus?
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Internal Carotid Artery compression
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What is the embryological origin of the Anterior Lobe?
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Oral Ectoderm (Stomodeum) -> Rathke's Pouch -> Anterior lobe
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What is the embryological origin of the Posterior Lobe?
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Neuroectoderm (Diencephalon)
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During what embryological time period does the Pituitary begin to form?
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3-8 weeks
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Describe the embryological formation of the Pituitary
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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 |
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From what Hypothalamic nucleus is Vasopressin (ADH) synthesized?
Oxytocin? |
ADH = Supraoptic
Oxytocin = Paraventricular |
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List the 7 hormones released from the Anterior Pituitary & also name the stimulators for each
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1. TSH <- TRH
2. LH <- GnRH, Estrogen 3. FSH <- GnRH, Estrogen 4. ACTH <- CRF 5. MSH <- CRF 6. GH <- GHRH 7. Prolactin <- TRH |
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What does the histology of the Posterior Pituitary contain?
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1. Glia = Pituicytes
2. Axons from Hypothalamus (Herring bodies = nerve terminals from which ADH & Oxytocin are released) |
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What are the 5 cell types in the Anterior Lobe?
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1. Somatotrophs GH
2. Lactotrophs = Prolactin 3. Corticotrophs = ACTH, POMC, MSH 4. Thyrotrophs = TSH 5. Gonadotrophs = FSH & LH |
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T or F: The majority of Pituitary tumors are associated with the MEN type 1 symdrome
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False = most are sporadic
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What is the most common tumor type of the Pituitary?
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Adenoma = benign & most are composed of a single cell type & secrete only 1 hormone
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What is the gross pathology associated with Pituitary Adenomas?
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1. Soft, well circumscribed
2. possible compression of adjacent structures 3. possible local invasion 4. Pituitary Apoplexy = bleeding within the gland |
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What is the microscopic pathology seen in Pituitary Adenomas?
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1. Sheets of Monotonous cells
2. sparse intervening Connective Tissue |
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What is the #1 type of Hyperfunctioning Pituitary Adenoma & accounts for 30% of Adenomas?
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Prolactinoma
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What are the main clinical features of Prolactinomas?
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Female of reproductive age = Amenorrhea & Galactorrhea
Men = loss of libido & infertility |
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Why do Prolactinomas cause Amenorrhea in women?
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Prolactin inhibits GnRH release -> decreased LH & FSH
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In what people are Prolactinoma's more easily diagnosed?
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women age 20-40
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What are the lab findings associated with Prolactinoma's
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1. increased Prolactin
2. decreased FSH & LH due to feedback inhibition by Prolactin on GnRH |
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In what people are Prolactinoma's usually larger?
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Older age = post-menopausal women don't notice amenorrhea
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What is the treatment for Prolactinoma's?
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Bromocriptine & Cabergoline = Dopamine agonists
**Dopamine from Hypothalamus inhibits Prolactin secretion from Anterior Pituitary |
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2nd most common Pituitary Adenoma with Hyperfunction
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Growth Hormone Adenoma
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What gene do 40% of Growth Hormone Adenoma's express?
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gsp oncogene (GTPase deficiency)
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What is the treatment for Growth Hormone Adenomas?
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Octreotide = mimics Somatostatin to inhibit GH secretion
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What are the clinical manifestations of Growth Hormone Adenoma's?
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1. Children = gigantism
2. Adults = Acromegaly |
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What are 2 pharmacologic agents that interfere with Dopamine secretion & could mimic a Prolactinoma?
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Methyl-dopa = increased alpha-2 receptor-mediated inhibition of SNS
Reserpine = blocks the storage of NE & Dopamine in secretory vesicles |
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What are the clinical features of Gigantism?
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Tall stature & long extremities due to the fact that Epiphyseal Plates have not closed yet
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What are the clinical features of Acromegaly?
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-Prominent Jaw
-Flat, broad forehead -Enlarged hands & feet **Epiphyseal plates have closed = increased LATERAL bone growth but not linear |
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What are associated findings in Growth Hormone Adenoma's?
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1. Diabetes Mellitus = GH stimulates gluconeogenesis
2. Muscle weakness 3. Hypertension 4. Congestive Heart Failure 5. Organomegaly |
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What do Corticotroph Adenoma's cause?
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Cushing Disease due to excess ACTH secretion resulting in Hypercortisolism
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Describe Nelson Syndrome
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-Bilateral adrenalectomy causes enlargement of a preexisting Pituitary Adenoma due to lack of Cortisol negative feedback on ACTH
-Hyperpigmentation due to MSH excess |
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Name for nonfunctional Adenomas but may cause mass effects
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Null Cell Adenoma
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How do Gonadotroph Adenoma's present clinically?
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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 |
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Discuss Pituitary Carcinoma's
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-Rare
-Nonfunctional -requires demonstration of metastases to distant sites = lymph nodes, bone, liver |
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What percent of the Pituitary has to be lost before Hypopituitarism is encountered?
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75% loss
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What are 3 etiologies of Hypopituitarism?
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1. tumors
2. ischemic necrosis 3. Empty Sella Syndrome |
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Discuss a Rathke Cleft Cyst
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Benign cyst that forms in the stalk or Anterior Lobe
- as it enlarges it can compress the normal gland & lead to hypopituitarism |
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List 4 Sellar Tumors that may cause Hypopituitarism
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1. Adenomas
2. Carcinomas 3. Metastases 4. Rathke Cleft Cyst |
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List 3 Suprasellar tumors that may cause Hypopituitarism
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1. Gliomas
2. Germinomas 3. Craniopharyngiomas |
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Most common intracranial germ cell tumor
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Germinoma
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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 4. AFP, bHCG, CEA |
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What is a Craniopharyngioma?
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Benign pituitary tumor derived from Rathke's Pouch remnants
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What is the most common cause of Hypopituitarism in children?
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Craniopharyngioma
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How are Craniopharyngiomas manifested in children? Adults?
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Children = endocrine abnormalities
Adults = visual abnormalities |
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What are the 2 histological variants of Craniopharyngioma?
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1. Adamantinomatous
2. Papillary |
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Describe the histology of Adamantinomatous Craniopharyngioma's
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-Stratified squamous epithelium
-Wet keratin -Calcifications -Cholesterol-rich fluid cyst ("motor oil") -Chronic inflammation -fingers extend into adjacent brain |
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Describe Sheehan Syndrome
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Postpartum Pituitary Necrosis
-massive blood loss at time of delivery causes hypoperfusion of the pituitary that has undergone physiological hyperplasia during pregnancy |
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What conditions could cause Ichemic Necrosis of the Pituitary resulting in Hypopituitarism?
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1. DIC
2. Sicke cell anemia 3. trauma 4. shock of any origin |
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What is the pathology seen in Ischemic necrosis of the Pituitary?
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Grossly atrophic = <0.1 gm
Fibrous Scar tissue |
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What is the most common cause of Empty Sella Syndrome?
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Diaphragmatic hernia
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Describe Primary Empty Sella Syndrome
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Pituitary atrophy is related to a compression by the CSF & Arachnoidea that invaginate into the Sella through a defect in the diaphragm
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What are 3 "other" causes of Empty Sella Syndrome?
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1. Sheehan's syndrome
2. Infarction of adenoma 3. Sellar mass treated by surgery/radiation |
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Describe the mnemonic for the most common causes of Hypopituitarism
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Invasion by tumors
Injury = head trauma Infarction = postpartum Sheehan syndrome Irradiation Immune diseases = Sarcoidosis; Autoimmune Hypophysitis Infection = basal meningitis, TB Inborn errors of metabolism Idiopathic |
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What congenital defect causes Hypopituitarism from patients not being able to make pituitary hormones?
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defect in Transcription Factor Pit-1 gene
-defective protein binds DNA but does not activate target genes |
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Invasive Pituitary Adenoma
-patient had 2-year history of dementia & visual impairment |
What is seen here?
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Pituitary Adenoma
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What is seen here?
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Pituitary Adenoma
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What is seen here?
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Rathke Cleft Cyst = benign cyst that forms in the stalk or Anterior lobe
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What is seen here?
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Germinoma = suprasellar tumor
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What is seen here?
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Craniopharyngioma = mass of cysts & solid areas
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What is seen here?
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Adamantinomatous Craniopharyngioma
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What is seen here?
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Papillary Craniopharyngioma
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What is seen here?
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Empty Sella Syndrome, primary type
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What is seen here?
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Pituitary Apoplexy
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What is seen here?
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