Path - Pituitary Flashcards
what are the associated syndromes of a lactotroph adenoma?
- galactorrhea, amenorrhea (in females)
- sexual dysfunction, infertility
what are the associated syndromes of a somatotroph adenoma?
- gigantism (children)
- acromegaly (adults)
what are the associated syndromes of a mammosomatotroph adenoma?
combined features of GH and prolactin excess
what are the associated syndromes of a corticotroph adenoma?
- Cushing syndrome
- Nelson syndrome
what are the associated syndromes of a thyrotroph adenoma?
hyperthyroidism
what are the associated syndromes of a gonadotroph adenoma?
hypogonadism, mass effects, hypopituitarism
MEN1 loss of function mutation is most commonly associated with what kind of pituitary tumors?
GH, prolactin, and ACTH adenomas
CDKN1B loss of function mutation is most commonly associated with what kind of pituitary tumor?
ACTH adenoma
GNAS gain of function mutation is most commonly associated with what kind of pituitary tumor?
GH adenoma
Protein kinase A gain of function mutation is most commonly associated with what kind of pituitary tumor?
GH and prolactin adenomas
HRAS gain of function mutation is most commonly associated with what kind of pituitary tumor?
pituitary carcinoma
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
pituitary adenoma
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
invasive pituitary adenoma
what is more common in macroadenomas than smaller tumors?
- invasiveness
- foci of hemorrhage and necrosis
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
pituitary adenoma
what distinguishes a pituitary adenoma from nonneoplastic anterior pituitary parenchyma?
cellular monomorphism and the absence of a significant reticulin network
which subtype of pituitary adenomas have a higher propensity for aggressive behavior, including invasion and recurrence?
atypical adenomas
- they demonstrate elevated mitotic activity and nuclear p53 expression
the majority of these adenomas are comprised of chromophobic cells with juxtanuclear localization of transcription factor PIT-1
sparsely granulated lactotroph adenomas
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
densely granulated lactotroph adenomas
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)
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
monomorphic, acidophilic cells that have strong cytoplasmic GH reactivity on immunohistochemistry
densely granulated somatotroph adenomas
chromophobe cells with considerable nuclear and cytologic pleomorphism and focal, weak staining for GH
sparsely granulated somatotroph adenomas
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
mammosomatotroph adenomas
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
corticotroph adenomas
what is the most common cause of hyperpituitarism?
anterior lobe pituitary adenoma
what is associated with distinct endocrine signs and symptoms?
functioning adenoma
what type of adenoma typically presents with mass effects, including visual disturbances?
nonfunctioning (silent) adenoma
these adenomas secrete prolactin and can present with amenorrhea, galactorrhea, loss of libido, and infertility
lactotroph
these adenomas secrete GH and present with gigantism in children and acromegaly in adults, impaired glucose tolerance and DM
somatotroph
these adenomas secrete ACTH and present with Cushing syndrome and hyperpigmentation
coricotroph
what is the most common form of clinically significant ischemic necrosis of the anterior pituitary?
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
why is the posterior pituitary so much less susceptible to ischemic injury?
because it receives its blood directly from arterial branches
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
craniopharyngiomas
NOTE: patients have an excellent recurrence-free and overall survival, malignant transformation into squamous carcinomas is exceptionally rare, usually occurs after irradiation
what are the two distinct histologic variants of craniopharyngiomas?
- adamantinomatous (CHILDREN, frequently calcifies)
2. papillary (ADULTS, rarely calcifies)
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
adamantinomatous craniopharyngioma
NOTE: the cysts often contain a cholesterol-rich, thick brownish-yellow fluid that has been compared to machine oil
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
papillary craniopharyngiomas
