Path - Pituitary

Question 1

what are the associated syndromes of a lactotroph adenoma?

Answer 1

• galactorrhea, amenorrhea (in females)

- sexual dysfunction, infertility

Question 2

what are the associated syndromes of a somatotroph adenoma?

Answer 2

• gigantism (children)

- acromegaly (adults)

Question 3

what are the associated syndromes of a mammosomatotroph adenoma?

Answer 3

combined features of GH and prolactin excess

Question 4

what are the associated syndromes of a corticotroph adenoma?

Answer 4

• Cushing syndrome

- Nelson syndrome

Question 5

what are the associated syndromes of a thyrotroph adenoma?

Answer 5

hyperthyroidism

Question 6

what are the associated syndromes of a gonadotroph adenoma?

Answer 6

hypogonadism, mass effects, hypopituitarism

Question 7

MEN1 loss of function mutation is most commonly associated with what kind of pituitary tumors?

Answer 7

GH, prolactin, and ACTH adenomas

Question 8

CDKN1B loss of function mutation is most commonly associated with what kind of pituitary tumor?

Answer 8

ACTH adenoma

Question 9

GNAS gain of function mutation is most commonly associated with what kind of pituitary tumor?

Answer 9

GH adenoma

Question 10

Protein kinase A gain of function mutation is most commonly associated with what kind of pituitary tumor?

Answer 10

GH and prolactin adenomas

Question 11

HRAS gain of function mutation is most commonly associated with what kind of pituitary tumor?

Answer 11

pituitary carcinoma

Question 12

soft, well-circumscribed tumor

• may be combined to the sell tursica, but with expansion they frequently erode the sell tursica and anterior clinoid processes
• larger lesions usually extend superiorly through the diaphragm sell into the suprasellar region, where they often compress the optic chiasm and adjacent structures

Answer 12

pituitary adenoma

Question 13

in as many as 30% of cases, the adenomas are not grossly encapsulated and infiltrate neighboring tissue such as the cavernous and sphenoid sinuses, dura, and on occasion, the brain itself

Answer 13

invasive pituitary adenoma

Question 14

what is more common in macroadenomas than smaller tumors?

Answer 14

• invasiveness

- foci of hemorrhage and necrosis

Question 15

uniform, polygonal cells arrays in sheets or cords

• supporting connective tissue (reticulin) is sparse, accounting for the soft, gelatinous consistency of many of these tumors
• mitotic activity is usually sparse
• cytoplasm may be acidophilic, basophilic, or chromophobic depending on type and amount of secretory product within the cells -> but is generally uniform throughout the tumor

Answer 15

pituitary adenoma

Question 16

what distinguishes a pituitary adenoma from nonneoplastic anterior pituitary parenchyma?

Answer 16

cellular monomorphism and the absence of a significant reticulin network

Question 17

which subtype of pituitary adenomas have a higher propensity for aggressive behavior, including invasion and recurrence?

Answer 17

atypical adenomas

- they demonstrate elevated mitotic activity and nuclear p53 expression

Question 18

the majority of these adenomas are comprised of chromophobic cells with juxtanuclear localization of transcription factor PIT-1

Answer 18

sparsely granulated lactotroph adenomas

Question 19

these adenomas are characterized by diffuse cytoplasmic PIT-1 expression localization
- prolactin can be demonstrated within the secretory granules in the cytoplasm of the cells using immunohist stains

Answer 19

densely granulated lactotroph adenomas

Question 20

what type of adenoma has the propensity to undergo dystrophic calcification, ranging from isolated psammoma bodies to extensive clacification of virtually the entire tumor mass (pituitary stone)

Answer 20

lactotroph adenomas

NOTE: prolactin secretion by functioning adenomas is usually efficient (even in microadenomas), and proportional, in that serum prolactin concentrations tend to correlate with the size of the adenoma

Question 21

monomorphic, acidophilic cells that have strong cytoplasmic GH reactivity on immunohistochemistry

Answer 21

densely granulated somatotroph adenomas

Question 22

chromophobe cells with considerable nuclear and cytologic pleomorphism and focal, weak staining for GH

Answer 22

sparsely granulated somatotroph adenomas

Question 23

these adenomas synthesize both GH and prolactin
- they resemble densely granulated pure somatotroph adenomas, but are distinguished by having immunohist reactivity for prolactin as well as GH

Answer 23

mammosomatotroph adenomas

Question 24

these are usually microadenomas at the time of diagnosis

• most often basophilic (densely granulated) and occasionally chromophobic (sparsely granulated)
• both variants stain positively with PAS becuase of the presence of carbohydrate in pro-opio-melanincortin (POMC = ACTH precursor molecule)
• they demonstrate variable immunoreactivity for POMC and it’s derivatives, including ACTH and b-endorphin

Answer 24

corticotroph adenomas

Question 25

what is the most common cause of hyperpituitarism?

Answer 25

anterior lobe pituitary adenoma

Question 26

what is associated with distinct endocrine signs and symptoms?

Answer 26

functioning adenoma

Question 27

what type of adenoma typically presents with mass effects, including visual disturbances?

Answer 27

nonfunctioning (silent) adenoma

Question 28

these adenomas secrete prolactin and can present with amenorrhea, galactorrhea, loss of libido, and infertility

Answer 28

lactotroph

Question 29

these adenomas secrete GH and present with gigantism in children and acromegaly in adults, impaired glucose tolerance and DM

Answer 29

somatotroph

Question 30

these adenomas secrete ACTH and present with Cushing syndrome and hyperpigmentation

Answer 30

coricotroph

Question 31

what is the most common form of clinically significant ischemic necrosis of the anterior pituitary?

Answer 31

Sheehan syndrome, aka postpartum necrosis

• during pregnancy, the anterior pituitary enlarges to almost twice its normal size
• this expansion is NOT accompanied by an increase in blood supply from the low-pressure venous system -> relative hypoxia -> potential ischemia
• if ischemia occurs, the area is resorbed and replaced by a nubbin of fibrous tissue attached to the wall of an empty sella

Question 32

why is the posterior pituitary so much less susceptible to ischemic injury?

Answer 32

because it receives its blood directly from arterial branches

Question 33

these tumors may be encapsulted and solid, but more commonly they are cystic and sometimes multiloculated
- they often encroach on the optic chiasm or cranial nerves, and can bulge into the floor of the third ventricle and base of the brain

Answer 33

craniopharyngiomas

NOTE: patients have an excellent recurrence-free and overall survival, malignant transformation into squamous carcinomas is exceptionally rare, usually occurs after irradiation

Question 34

what are the two distinct histologic variants of craniopharyngiomas?

Answer 34

1. adamantinomatous (CHILDREN, frequently calcifies)

2. papillary (ADULTS, rarely calcifies)

Question 35

nests or cords of stratified squamous epithelium embedded in a spongy reticulum that becomes more prominent in the internal layers

• “palisading” of the squamous epithelium is frequently observed at the periphery
• compact, lamellar keratin formation (wet keratin) is a diagnostic feature
• dystrophic calcification frequently found
• cyst formation, fibrosis, chronic inflammation present
• tumors extend fingerlets of epithelium into adjacent brain, where they elicit a brisk glial reaction

Answer 35

adamantinomatous craniopharyngioma

NOTE: the cysts often contain a cholesterol-rich, thick brownish-yellow fluid that has been compared to machine oil

Question 36

these craniopharyngiomas contain both solid sheets and papillae lined by well-differentiated squamous epithelium

• tumors usually lack keratin, calcification and cysts
• squamous cells of the solid sections of the tumor lack the peripheral palisading and do not typically generate a spongy reticulum in the internal layers

Answer 36

papillary craniopharyngiomas