CM- Pituitary Tumors

Question 1

What are the 2 components of the pituitary gland?

Where does it rest?

Answer 1

Anterior [adenohypophysis] and posterior [neurohypophysis]

it rests in the sella turcica and is entirely surrounded by dura except for the diaphragm sella where it receives neural input from the hypothalamus

Question 2

What is the anterior/inferior boundary of the pituitary?
What is the posterior border?
What are the lateral borders?
What is the superior border?

Answer 2

Anterior/inferior = sphenoid sinus

Posterior = bony dorsum sella

Lateral = cavernous sinuses [venous blood, carotid arteries, oculomotor, trochlear, abducens, 2 parts of trigeminal]

Superior = diaphragma sella [above which is optic chiasm with suprasellar cistern]

Question 3

What cell in the ant. pituitary is predominantly under inhibitory control?
What does this mean if there is a tumor or disease process that disrupts the pituitary stalk?

Answer 3

Prolactin is under inhibitory control by dopamine.
If there is disruption of the pituitary stalk, it will lead to ELEVATED prolactin and insufficient levels of the other ant. pituitary hormones.

Question 4

What is the incidence of clinically significant pituitary adenomas?
What are the 3 ways they usually present?

Answer 4

3/100,000 per year [very low]

They present with:

1. overproducing ant. pituitary hormones [HYPERSECRETION]
2. visual loss or ant. pituitary insufficiency due to MASS EFFECT
3. pituitary apoplexy

Question 5

What is the basis of medical therapy for hypersecreting pituitary adenomas?

Answer 5

Ant. pituitary adenomas are well-differentiated so they will be responsive to excitatory and inhibitory stimuli [just like normal pituitary cells]

Question 6

What are 2 situations where there may be hyperplasia of one or more ant. pituitary cell lines that can be mistaken for a tumor?

Answer 6

1. pregnancy

2. puberty

Question 7

Originally the classification of pituitary adenomas was based on microscopic observation of staining. What 3 classes were used?
What system is used now?

Answer 7

1. chromophobe = colorless, largest group, endocrinologically inactive
2. eosinophilic adenomas = GH
3. basophilic adenoma = ACTH

Now we use immunohistochemical staining to determine the hormone secreted by the adenoma

Question 8

What do the vast majority of small, asymptomatic pituitary adenomas secrete?

Answer 8

nothing

Question 9

What are the most frequent symptomatic pituitary adenomas from most to least?

Answer 9

1. prolactin
2. GH
3. multiples [GH+PRL, GH+PRL+TSH]
4. ACTH

Question 10

Endocrine hypersecretion is NOT a function of size of the adenoma entirely. What hypersecreting adenoma is often so small that it is below the resolution of MR?

Answer 10

ACTH secreting adenoma

Question 11

A child presents with gigantism. What is the pituitary adenoma hypersecreting?
What would you have seen in an adult?

Answer 11

GH-secreting adenoma.
The child has gigantism because growth was stimulated before the closing of the epiphyseal plates

If this was an adult, we would see:

1. acromegaly [growth of acral bones, face, finger, feet],
2. DM due to antagonism of insulin
3. hypertension

Question 12

A patient presents with glucose intolerance, hypertension, osteoporosis, fat redistribution, and easy bruising. What hormone is being over secreted?

Answer 12

This is Cushing disease where there is oversecretion of ACTH.

Pituitary adenoma hypersecretes ACTH, which stimulates overproduction of cortisol by adrenal cortex ,

Question 13

A female presents with breast discharge [galactorrhea] and amenorrhea and infertility.
What hormone is in excess?
What would a man with this present with?

Answer 13

Prolactin-secreting adenoma

Men would have:

1. infertility
2. erectile dysfunction

Question 14

What are the 3 major ways a pituitary adenoma may cause symptoms by virtue of mass effect?

Answer 14

1. produce atrophy of surrounding non-neoplastic portion of ant. pituitary–> pituitary insufficiency
2. distortion of the optic chiasm can cause bitemporal hemianopsia [loss of peripheral] which can lead to panhypopituitarism and blindness
3. Lateral growth can go into cavernous sinus and affect:
   - abducens, oculomotor, trochlear = diplopia
   - 2 divisions of trigeminal = facial numbness

Question 15

What is pituitary apoplexy?
What are the symptoms if it is:
1. small
2. fills and enlarges the sella, but not optic chiasm
3. large and involves chiasm and 3rd ventricle

Answer 15

It is when infarction [and possible intratumoral hemorrhage] of the pituitary adenoma causes acute swelling of the tumor.

Small = headache

Fills sella, no chiasm = diplopia due to abducens, oculomotor involvement in cavernous sinus

Large, 3rd ventricle/chiasm = obtundation and blindness [emergent surgical intervention]

Question 16

A patient presents with serum prolactin of greater than 200. What should treatment be for the patient?

Answer 16

1. trial of anti-secretory medication like a dopamine agonist [bromocryptine, cabergoline]

If this fails:
2. surgical intervention

Question 17

What is treatment for GH and ACTH secreting tumors?

Answer 17

1. complete removal of the tumor if possible [use transsphenoidal approach]
2. radiation and anti-secretory meds used for those who couldn’t be cured with surgery

Question 18

Transsphenoidal approach provides better access to tumors in what anatomic region?

Answer 18

tumors contained entirely in the sella.

This approach gives better access than a craniotomy and permits the removal of the suprasellar portion of most tumors w/o messing with the optic nerve

Question 19

When do you consider transcranial surgical approach to remove a pituitary adenoma over a transsphenoidal approach?

Answer 19

When the tumor is eccentric, predominantly suprasellar

Question 20

What should be done postoperatively for patients who have had removal of pituitary adenomas?

Answer 20

Recurrence rate of pituitary macroadenomas (>1cm) is significantly lowered in patients who got :
Fractionated radiation therapy post-op

However, it is withheld to avoid long term radiation effects on the hypothalamus.

Give stereotactic radiosurgery or intensity modulated radiation therapy if necessary

Question 21

What is craniopharyngioma?

What cells does it arise from?

Answer 21

It is a locally invasive tumor that arise from squamous cells of the infundibulum and pituitary stalk