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Pathology of the Pituitary Gland
Pathology of pituitary dysfunction
41
Pathology
Professional
04/23/2011

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Term
Mutations involving _______ are probably the best-characterized molecular abnormalities in pituitary adenomas.
Definition
G proteins
Term
The a-subunit of a G protein binds...
Definition
guanine nucleotide
Term
What is GNAS? Mutations can cause what sort of problem? Which types of adenomas has this been associated with?
Definition
gene for G-protein alpha subunit, mutation can interfere with intrinsic GTPase activity and lead to constitutive activation and generation of cAMP. 40% of somatotroph adenomas have these mutations. Also seen in corticotroph adenomas. NOT seen in thyrotroph, lactotroph, or gonadotroph because they don't use cAMP-dependent pathways
Term
Are most pituitary adenomas sporadic or familial?
Definition
overwhelming majority are sporadic
Term
Name the 4 genes identified as a cause of familial pituitary adenomas.
Definition
MEN1, CDKN1B, PRKAR1A, AIP
Term
What is MEN1, and what do mutations cause?
Definition
Gene product is tumor suppressor menin, those with MEN1 syndrome get tumors in multiple endocrine organs including pituitary. Rare in sporadic cases of pituitary adenomas.
Term
The gene product is cell cycle checkpoint regulator p27 or KIP1, mutations are responsible for subset of pts with MEN1-like syndrome who lack MEN1 abnormalities. What is the gene?
Definition
CDKN1B
Term
What is Carney complex?
Definition
Auto-dom disorder, mutation of PRKAR1A, protein kinase A regulatory subunit 1A. Characterized by pituitary and other endocrine tumors. Gene encodes a tumor suppressor that regulates activity of protein kinase A, loss of it leads to inappropriate activation of cAMP cellular targets.
Term
Testing for ____ is typically recommended for CH adenomas arising in younger patients.
Definition
AIP
Term
Abnormalities in cyclin D1, p53, RB1 are associated with what consequence? Activating mutations of HRAS are observed in which conditions?
Definition
Aggressive tumors. Rare pituitary carcinomas.
Term
What distinguishes an invasive adenoma? This is seen in approx what percentage of cases?
Definition
tumor is not grossly encapsulated and infiltrates the neighboring tissues. Macroadenomas tend to be invasive more frequently.
Term
What accounts for the soft, gelatinous nature of most pituitary adenomas? What distinguishes it from the rest of the normal parenchyma?
Definition
Reticulin is sparse. Cellular monophorphism and sparse reticulin distinguish it.
Term
A subset of adenomas, classified as atypical adenomas, display which features?
Definition
brisk mitotic activity, staining of greater than 3% of nuclei with Ki-67 proliferation marker, extensive p53 immunoreactivity. They have higher propensity for aggressive behavior.
Term
What is the most frequent type of hyperfunctioning pituitary adenoma?
Definition
prolactinomas
Term
Prolactinomas have a tendency to undergo what sort of process?
Definition
dystrophic calcification, from isolated psammoma bodies to extensive calcification - pituitary stone
Term
What causes amenorrhea, galactorrhea, loss of libido and infertility?
Definition
prolactinoma
Term
What cause underlies almost 25% of cases of amenorrhea and is more readily diagnosed in women from 20-40?
Definition
Prolactinoma
Term
Prolactinemia can result from ________ hyperplasia, such as when there is an interference with normal ______.
Definition
lactotroph, dopamine inhibition of prolactin secretion.
Term
Any mass in the suprasellar compartment can disturb the normal inhibitory effect on...
Definition
prolactin secretion
Term
Densely granulated somatotroph adenomas have which features? What about sparsely granulated? Which one do bihormonal mammosomatotroph adenomas resemble?
Definition
monomorphic, acidophilic, strong cytoplasmic GH reactivity, cytokeratin staining in perinuclear distribution. Chromophobe cells, pleomorphism, weak focal staining for GH. Usually the densely granulated version.
Term
Describe what corticotroph adenomas tend to look like at the time of diagnosis. They have variable reactivity for which substances?
Definition
Usually small microadenomas, often basophilic or densely granulated, rarely chromophobic or sparsely granulated. POMC, ACTH, B-endorphin.
Term
A large destructive adenoma develops in patients after surgical removal of the adrenal glands for tx of Cushings syndrome. This pt has which syndrome? He would present with what sort of symptoms? Why might his skin look odd?
Definition
Nelson syndrome, mass effects (no hypercortisolism), hyperpigmentation
Term
How do unusual plurihormonal adenomas usually behave?
Definition
aggressively
Term
Why can gonadotroph adenomas be difficult to recognize?
Definition
they secrete hormones inefficiently and variably, and do not usually cause a recognizable clinical syndrome
Term
Gonadotroph adenomas are associated with paradoxical....
Definition
hypogonadism (decreased energy, libido, amennorhea)
Term
Demonstration of craniospinal or systemic mets is a sine qua non of a pituitary...
Definition
carcinoma
Term
Majority of pituitary carcinomas have what properties?
Definition
functional, secreting ACTH and prolactin most commonly
Term
Hypopituitarism accompanied by evidence of posterior pituitary dysfunction in the form of DI is almost always __________ in origin.
Definition
hypothalamic in origin
Term
If I had a structure lined by ciliated cuboidal epithelial cells with occasional goblet cells and anterior pituitary cells, that accumulated proteinaceous fluid and expanded, compromising the rest of my pituitary gland, what might I have?
Definition
a Rathke cleft cyst
Term
What syndrome involves a defect in the diaphragma sella that allows arachnoid mater and cerebrospinal fluid to herniate into the sella, classically occurring in obese women with a hx of multiple pregnancies?
Definition
primary empty sella
Term
What is secondary empty sella?
Definition
A mass enlarges the sella, then it is surgically removed or undergoes spontaneous necrosis
Term
Mutation of POU1F1 leads to...
Definition
(pituitary-specific homeobox gene) combined pituitary hormone deficiency
Term
Gonadotropic deficiency leads to...
Definition
Amenorrhea and infertility in women. Decreased libido, impotence and loss of public and axillary hair in men.
Term
One of the most frequent causes of SIADH is ectopic secretion by...
Definition
malignant neoplasms, particularly SCC of lung
Term
Tumors in which region can cause hypo or hyperfunction of the anterior pituitary, DI or combinations?
Definition
suprasellar tumors
Term
What are the most common suprasellar tumors?
Definition
fliomas and craniopharyngiomas
Term
What is the age distribution for craniopharyngiomas? Abnormalities of which signaling pathways have been reported?
Definition
bimodal - 5-15 and over 65. WNT signaling including B-catenin mutations
Term
Which type of tumor does this describe: Radiological demonstrable calcification, nests or cords of stratified squamous epithelium embedded in a spongy reticulum, palisading of the squamous epithelium in the periphery, compact lamellar "wet" keratin?
Definition
adamantinomatous craniopharyngioma
Term
What type of fluid is often found in adamantinomatous craniopharyngiomas? What extends into the adjacent brain?
Definition
cholesterol-rich, thick brown-yellow fluid compared to machine oil, extends fingerlets of epithelium into adjacent brain where they elicit a brisk glial reaction
Term
Papillary craniopharyngiomas lack which features?
Definition
keratin, calcification, cysts, peripheral palisading, spongy reticulum
Term
What is the prognosis of craniopharyngiomas?
Definition
generally great, recurrence-free. Larger are more invasive but this doesn't impact survival. Malignant transformation into squamous carcinomas is very rare, and usually occurs after radiation.
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