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Pathology Ch 24
The Endocrine System - Pituitary Gland
31
Pathology
Professional
05/16/2012

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Cards

Term
MEN1 gene
Definition

encodes tumor suppressor gene merlin

responsible for familial pituitary adenoma syndrome

on chromosome 11q13

Term
CDKN1B
Definition

gene responsible for "MEN1-like" syndrome

located on chr 12p13

Term
PRKAR1A
Definition

mutation causes Carney complex

on chr 17q24

autosomal dominant disorder of pituitary adenomas

loss of functional protein leads to inappropriate activation of cAMP cellular targets

Term
AIP
Definition

mutation responsible for familial pituitary adenomas

incomplete penetrance

on chr 11q

pts often present with acromegaly due to an underlying GH-secreting adenoma

typically affects pts <35 yrs

Term
Typical pituitary adenoma
Definition

soft, well-circumscribed lesion that may be confined to the sella turcica; larger growths compress the optic chiasm --> bitemporal hemianopia

relatively uniform, polygonal cells arrayed in sheets or cords

supporting connective tissue is sparse = soft gelatinous consistency

cellular monomorphism and absence of reticulin network

symptoms are related to endocrine abnormalities and mass effects

Term
Invasive adenoma
Definition

lesion of the pituitary that invades neighboring tissues

usually macroadenomas

foci of hemorrhage and necrosis are more common

Term
Atypical adenoma
Definition

adenoma with brisk mitotic activity and staining greater than 3% of nuclei with Ki-67

extensive nuclear p53 immunoreactivity

invasive, aggressive behavior is more common

Term
Pituitary apoplexy
Definition

acute hemorrhage in an adenoma

may cause sudden onset of excruciating headache, diplopia, and hypopituitarism

may even cause cardiovascular collapse, loss of consciousness, sudden death

Term
Prolactinomas
Definition

most frequent type of hyperfunctioning pituitary adenoma

acidophilic or chromophobic cells

tend to undergo dystrophic calcification: psammoma bodies, extensive calcification ("pituitary stone")

amenorrhea, galactorrhea, loss of libido, infertility

tx with bromocriptine

Term
Hyperprolactinemia
Definition
physiologic condition during pregnancy, lactation
Term
Lactotrophic hyperplasia
Definition
hyperprolactinemia caused by interference with normal dopamine inhibition of prolactin
Term

Somatotroph adenomas

(GH cell adenomas)

Definition

densely (monomorphic, acidophilic) or sparsely (pleomorphhic, chromophobic) granulated pituitary adenoma w/ persistently elevated IFG-1/somatomedin C

presents as gigantism (pre-epiphyseal closure) or acromegaly (post-epiphyseal closure)

gonadal dysfunction, DM, hypertension, arthritis, congestive heart failure, increased risk of GI cancers

failure to suppress GH production after oral gluclose load = acromegaly (hyperostosis, prognathism)

Term
Densely granulated somatroph adenoma
Definition

adenoma composed of monomorphic, acidophilic cells

retain strong cytoplasmic GH reactivity on immunostain

cytokeratin staining in a perinuclear distribution

Term
Sparsely granulated somatotroph adenoma
Definition

pure GH-cell containing adenoma composed of chromophobe cells with considerable nuclear and cytologic pleomorphism

focal, weak staining for GH

Term

Corticotroph Adenomas 

(ACTH cell adenomas)

Definition

most often basophilic (densely granulated), occasionally chromophobic (sparsely granulated)

positive stain with PAS due to POMC presence

hypercortisolism (Cushing syndrome)

 

Term
Cushing disease
Definition
hypercortisolism secondary to excessive ACTH production by a pituitary adenoma
Term
Nelson syndrome
Definition

occurs after surgical removal of the adrenals, often for tx of Cushing syndrome

loss of inhibitory effect of adrenal corticosteroids on a preexisting corticotroph microadenoma

present with mass effects of pituitary tumor; may also be hyperpigmentation

Term

Gonadotroph adenoma

(LH and FSH producing)

*may actually impair LH secretion, FSH is primary secretion

Definition

secrete hormones inefficiently and variably

usually identified when increasing size causes neurologic symptoms (impaired vision, headaches, diplopia, pituitary apoplexy)

can also cause decreased energy, libido, amenorrhea due to secondary gonadal hypofunction

Term

Thyrotroph adenomas

(TSH producing)

Definition
rare adenoma that causes hyperthyroidism
Term
Nonfunctioning pituitary adenoma
Definition

adenomas that do not secrete hormone

typical presentation is due to mass effects

may cause hypopituitarism

Term
Hypopituitarism
Definition

can be caused by tumors, injury, hemorrhage, surgery, radiation, pituitary apoplexy, necrosis, Rathke cleft cyst, empty sella syndrome, genetic defects, hypothalamic lesions, or inflammatory disorders

usually accompanied by diabetes insipidus

occurs when 75% of the parenchyma is lost

Term
Sheehan syndrome
Definition

hypopituitarism caused by postpartum necrosis of the anterior pituitary

ischemic, necrotic tissue is replaced by fibrous tissue attached to the wall of an empty sella

Term
Rathke cleft cyst
Definition

cysts lined by ciliated cuboidal epithelium with occasional goblet cells and anterior pituitary cells

compromises pituitary function

Term
Primary empty sella syndrome
Definition

presence of an enlarged, empty sella tucica

defect in the diaphragm sella that allows arachnoid mater and CSF to herniate into the sella, resulting in expansion of the sella and pituitary compression

usually obese women with a history of multiple pregnancies

visual field defects, hyperprolactinemia, hypopituitarism

 

Term
Secondary empty sella syndrome
Definition

presence of an enlarged, empty sella tucica

caused by a mass that enlarges the sella but is either removed by surgery or undergoes spontaneous necrosis

leads to hypopituitarism

Term
Central diabetes insipidus
Definition

ADH deficiency

polyuria, polydipsia

caused by trauma or spontaneous

increased serum sodium and osmolality

Term
Nephrogenic diabetes insipidus
Definition

result of renal tubular unresponsiveness to ADH

polyuria, polydipsia

caused by trauma or spontaneous

increased serum sodium and osmolality

Term
SIADH
Definition

hyponatremia caused by ADH excess

usually caused by secretion of ectopic ADH by malignant neoplasms (esp. small-cell carcinomas of the lung), drug-induced ADH secretion, and various CNS disorders

hyponatremia, cerebral edema, neurologic dysfunction

Term
Adamantinomatous craniopharyngioma
Definition

hypothalamic suprasellar tumor most often observed in children; thought to be vestigial Rathke's pouch

radiologically demonstrable dystrophic calcifications

nests or cord of stratified squamous epithelium in a spongy reticulum that becomes increasingly prominent in internal layers; palisading pattern

cysts with cholesterol-rich, thick brownish-yellow, machine oil-like fluid

Term
Papillary craniopharyngioma
Definition

hypothalamic suprasellar tumor most often observed in adults > 65; thought to be vestigial Rathke's pouch

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

usually lack keratin, calcification, and cysts

no palisading epithelium or spongy reticulum

Term
GNAS mutation - G protein mutations
Definition

best characterized abnormality in pituitary adenomas

leads to constitutive receptor activity and increased cAMP levels

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