Pituitary pathology -Guo

Question 1

What does an endocrine cell cytologic sample look like? Histologic?

Answer 1

cytology: salt and pepper (normally fine needle aspirate)
histology: no lumen, cell walls

Question 2

What are the chromophobe cells of the anterior pituitary?

Answer 2

prolactin secreting

Question 3

What is the stalk effect? What will the resulting hormone levels be?

Answer 3

when a mass copresses the pituitary stalk, blocking the secretion from the hypothalamus

all pituitary hormones will be decreased, but prolactin will be increased (due to a loss of the DA inhibition)

Question 4

What is the most common cause of hyperpituitarism?

Answer 4

adenomas in the anterior lobe (then hyperplasia, carcinoma, ectopic hormone production and hypothalamic disorders)

Question 5

What is the difference between a micro and macro adenoma?

Answer 5

micro=<1 cm

macro=1cm+

Question 6

What does an adenoma look like compared to normal histology?

Answer 6

adenoma=monoclonal (1 cell type), loss of reticular network, rare or absent mitosis

normal=multi-clonal, reticular network around cell walls

hyperplasia: expanded reticular network.

Question 7

What is the most common adenoma in the pituitary?

Answer 7

prolactin adenoma

Question 8

What are some features of prolactinoma?

Answer 8

chromophobe or weakly acidophillic, functional

> 200ng/ml=prolactinoma (30-200ng/ml=other cause–> stalk effect)

Galactorrhea, amenorrhea, decrease libido and infertility

Question 9

What are some characteristics of a GH secreting adenoma (somatotroph adenoma)?

Answer 9

• 40% with GNAS mutation (gene 20q13)–> inhibition of GTPase causing an increase in cAMP
• persistent GH secretion (may be mixed with prolactin)
• delayed symptoms–> large adenomas
• gigantism or acromegaly
• diabetes, arthritis, osteoporosis, HTN, mm weakness
• persistent GH stimulates IGF-1–> glucose tolerance and DM

Question 10

What disease results from a corticotroph cell adenoma?

Answer 10

elevated ACTH–> cushing’s disease

Question 11

How is a prolactinoma diagnosed?

Answer 11

PRL >200 and brain MRI

harder to dx in males because do not show period changes (only decreased libido and impotence)

Question 12

What are 3 other important differentials to consider for a prolactinoma?

Answer 12

primary hypothyroidism–> can cause a increase in TSH and TRH (because low T4)–> this can cause an increase in PRL

antipsychotic meds that block DA can also cause hyperprolactinemia

pregnancy

Question 13

How is a GH secreting adenoma diagnosed?

Answer 13

failure to suppress GH level with an oral load of glucose

IGF-1 levels are elevated.

Question 14

What is Nelson syndrome?

Answer 14

can result if a pt with undiagnosed pituitary ACTH secreting adenoma undergoes an adrenalectomy–> the pituitary adenoma will have aggressive growth due to the loss of feedback inhibition

excess ACTH can cause darkening of skin, and will also have HA and visual difficulties due to the size of the tumor

Question 15

What is a pituitary apoplexy?

Answer 15

• normally a non-functioning adenoma
• large
• can have intrasellar hemorrhage due to vascular erosion that causes problems
• sudden HA, visual field defect and acute hormonal deficiency.

Question 16

What is Empty Sella Syndrome?

Answer 16

a condition due to an incompetent diaphragm sella that allows herniation of the arachnoid into the sella turcica and eventual atrophy of the pituitary gland.

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Question 17

What are some characteristics of a craniopharyngioma?

Answer 17

• ages 5-15 and 60+
• derived from rathkes pouch remnants
• suprasellar or intrasellar, often cystic with calcification
• symptoms may be delayed >20 yrs.
• symptoms: hypo or hyper function of pituitary, visual disturbances, diabetes insipidus
• benign and slow growing

Question 18

What is necessary for hypopituitary diagnosis? what can cause this?

Answer 18

-loss of >75% of ant pit

• causes: 1. nonsecretory pit adenoma
  2. ischemic necrosis (sheehan’s syndrome (post partum hemorrhage), sickle cell anemia, DIC, pituitary apoplexy)
  3. empty sella syndrome
  4. radiation or surgery
  5. autoimmune hypophysitis
  6. inflammatory (TB)
  7. craniopharyngioma

Question 19

What is Sheehan’s syndrome?

Answer 19

pregnancy can lead to the elevation of PRL-secreting cells which will cause pituitary hyperplasia and enlargement (no increase in blood supply)

if a hemorrhagic emergency takes place and the BP drops, the pituitary is vulnerable to ischemia/necrosis

-can result in lactational failure and hypoglycemia followed by amenorrhea, fatigue

Question 20

What is SIADH (syndrome of inappropriate ADH)?

Answer 20

hyper functioning posterior pituitary causing increased ADH levels –> water retention and hyponatremia

causes:

• ectopic ADH (small cell lung ca)
• non-neoplastic diseases of lung
• CNS disorders
• injury to hypothalamus or posterior pituitary

-can cause HA, anorexia, committing, confusion, coma, seizures.

Question 21

What is diabetes insidious due to?

Answer 21

ADH deficiency

• excessive urination, dilute urine
  causes: head trauma, tumor, inflammation and tumors in the pituitary or hypothalamus