Pituitary pathology

Question 1

causes of hypopituitarism?

Answer 1

• postsurgical, postirridation
• cysts and tumors
• ischemia/hemorrhage, inflammation
• empty sella syndrome
• gene defect

Question 2

Which lobe of pituitary does infarction usually involve?

Answer 2

anterior d/t vascular supply

** 75% of lobe must be lost for symptoms to occur

Question 3

what are some causes of pituitary infarction?

Answer 3

• sheehan syndrome
• cerebral infarction
• pituitary hemorrhage
• increased intracranial pressure

Question 4

what is sheehan syndrome?

Answer 4

postpartum hypopituitarism d/t necrosis of the gland from peripartum hemorrhagic shock

** it is rare

Question 5

Symptoms of sheehan syndrome?

Answer 5

• lactation failure, amenorrhea, asthenia (lack of energy and strength)
• premature aging, dryness and hypopigmentation of skin, genital and axillary hair loss

Question 6

Describe what you see. what does this show? what would high power view show?

Answer 6

This shows pituitary infarct.

The pinkish stuff is the large zone of dead parenchyma and the adjacent purple stuff is the thin subscapular strip of surviving parenchyma

* the picture here shows pituitary infarct above the line (pink, architecture of cell/tissue not rlly visible)

** high power view would show coagulative necrosis of the parenchymal cells

Question 8

What are some inflammatory lesions of the pituitary?

Answer 8

• acute inflammation like sinusitis and osteomyelitis
• granulomatous (TB, fungal ,sarcoid, idiopathic giant cell granuloma)
• lymphocytic (autoimmune)

Question 9

Describe what you see. what is this? where does it usually occur? high power would show?

Answer 9

• Sarcoidosis of the pituitary–tight naked granulomas that are very cohesive but lacking the rim of lymphocytes usually around granulomas
• in the cranium it is usually located near the base of the brain aka basal
• high power as shown here shows the tight naked granuloma with epithelioid histiocytes and a multinucleated giant cell

**dont assume it’s not infectious until getting hx and staining for tb and fungi

Question 10

causes of hyperpituitarism?

Answer 10

• hyperplasia
• pituitary adenoma
• ectopic secretion by nonpituitary tumor
• hypothalamic disorder

Question 11

general pituitary hyperplasia info

Answer 11

• uncommon
• primary vs secondary
• nodular or diffuse pattern of gland involvment
• increase in cell #
• e.g. ACTH hyperplasia in addison’s disease

Question 12

pituitary adenoma general principles

Answer 12

1) pituitary adenomas are the MCC of hyperpituitarism
2) pituitary adenomas = 10% of intracranial neoplasms
3) MC in middle age (35-60yo)
4) usually isoated but can be part of multiple endocrine neoplasia (MEN) syndromes
5) functional pituitary adenomas get detected earlier

**they are in sella turcica and can press on optic chiasm and cause bitermporal hemoanopsia

Question 13

what are the types of pituiary adenomas in order of occurence?

Answer 13

1) nonfunctioning 30%
2) lactotrophs/prl secreting 30%
3) corticotrophs, acth secreting 15%
4) gonadotrophs, LH or FSH secreting 10%
5) Somatotrophs, GH secreting 5%

Question 14

what are the genetic alterations that occur in pituitary adenomas?

Answer 14

• mutations that lead to G-protein (composed of alpha and beta subunits) hyperactivity occur in pituitary, thyroid and parathyroid adenomas.
• GNAS gene (normally encodes alpha subunit of Gs) mutation cuases constituitve activation of Galpha –> persistent generation of cAMP and unchecked cellular proliferation.

Question 15

What is prolactinoma?
Epidemiology?

Symptoms?

Answer 15

• pituitary adenoma producing prolactin, the most common type of pituitary adenoma
• uncommon, most in middle aged FEMALES
• most sporadic but a few part of MEN-1 syndrome
• symptoms: amenorrhea and galactorrhea

Question 16

Histopathology of prolactinoma??

Answer 16

• sheet like growth pattern
• relative cellular monomorphism
• loss of typical reticulin fiber network
• functional status cant be predicted from histo appearance but immunohistochemical stains can be confirmatory!

Question 17

what is SIADH?
what causes it?

symptoms?

Answer 17

• ADH excess caused by ectopic secretion by tumor (small cell lung cancer) usually
• symptoms: HYPOnatremia, cerebral edema, neurologic dysfunction

Question 18

What is diabetes insipidus?

what causes it?

symptoms?

Answer 18

• ADH deficiency
• cause can be spontaneous or as a result of various conditions including trauma, tumors, inflammatory disorders or post surgical
• symptoms include excretion of large volume of dilute urine, HYPERnatremia, and increased osmolarity.

Question 19

What is craniopharyngioma?

Epidemiology?

symptoms?

genetics?

Answer 19

• slow growing neoplasm thought to arise from vestigial remnant of Rathke pouch (give rise to AP)
• 1-5% of intracranial tumors; bimodal age distribution
• Symptoms: headaches and visual disturbances
• abnormalities of WNT signaling –> activating mutations of the gene encoding beta catenin

** two types: adamantinomatous in children and papillary in adults