PITUITARY ADENOMA Flashcards
Define pituitary adenomas:
tumors that derive from one of the 5 types of pituitary hormone producing cells within the anterior lobe of pituitary
>95% are sporadic, <5% are genetic
what are the size classifications of pituitary adenomas?
microadenoma: <10 mm (functional)
macroadenoma: > or equal to 10 mm (mass effect)
how else are pituitary adenomas classified?
secretory and non-secretory
pituitary adenoma epidemiology:
- most commonly dx btwn 30-60 y/o
- > 60% benign, 30% invasive, <1% carcinomas
- cause 60% all cases of hypopituitarism
pituitary adenoma pathophys:
growth of adenoma will compress surrounding glandular tissue
most adenomas will arise from a single pituitary cell type
what type of adenoma are 60% of all pituitary adenomas?
secretory adenomas
lactotroph adenomas
40%, most common
increased prolactin leads to hyperprolactinemia
somatotroph adenomas
what do they lead to
also most common
increased growth hormone leads to acromegaly or gigantism
corticotroph adenomas
what do they increase and lead to?
increased adrenocorticotropic hormone (ACTH) leading to cushings
thyrotroph adenomas
rare
increased TSH leads to 2ndary hyperthyroidism
what is the most common type of adenoma that is derived from multiple types of pituitary cells secreting more than 1 hormone?
somatotroph + lactotroph
often atypical and/or malignant forms of adenomas, which transform into aggressive and tx-resistant carcinomas
what are 40% of all pituitary adenomas?
non-secretory
> 80% of non-secretory cases derive from what type of cells of the pituitary
gonadotroph
definition of hypopituitarism:
decreased secretion of one, some, or all anterior pituitary hormones
what are the causes of hypopituitarism?
three things
- most common: adenoma
- infarct
- 2ndary sempty sella syndrome (head trauma, infxn, radiation therapy, pituitary surgery, Sheehan syndrome)
what is the pathophys of hypopituitarism?
destruction of >75% pituitary tissue resulting in sequential loss of anterior pituitary hormones.
sx depend on deficient hormones
what are the most common pituitary hormone deficiencies?
gonadotropins resulting in hypogonadism in both men and women
what is the clinical presentation of microadenomas <10?
non secretory is asymptomatic
secretory causes hyperpituitarism
- sx depend on effects that excessive hormone exerts on peripheral target organs
- hyperprolactinemia, acromegaly or gigantism, cushings, 2ndary hyperthyroidism
what is the clinical presentation of non-secretory macroadenomas >or equal to 10?
MASS EFFECT SYMPTOMS
1. bitemporal hemianopsia- diminished vision in bilateral temporal fields
2. diplopia from compression of optic chiasma nerve
3. opthalmoplegia- paralysis of CN 3,4,6 (extraocular eye muscles); results from invasion of cavernous sinus
4. headache
5. vomitting w/o nausea
6. AMS
7. pituitary apoplexy- sudden loss of blood supply to pituitary gland, leading to tissue necrosis and loss of fxn d/t sudden hemorrhage into adenoma -> excruciating HA and diplopia
what is the clinical presentation of secretory macroadenomas >or equal to 10?
hyperpituitarism
sx depend on hormone-specific effects
other hormones are deficient d/t pituitary tissue destruction
mass effect sx
how are most microadenomas diagnosed?
incidentally
what is clinical suspicion based on?
sx caused by excessive hormone in addition to mass effect symptoms.
this combo suggests pituitary mass
what is the gold standard imaging to confirm sellar masses, size, and location?
contrast MRI
(CT used if MRI contraindicated-> pts w/ pacemaker or metallic implants)
What laboratory testing is done?
- basal prolactin levels to assess prolactinomas
- insulin-like GF-1 levels to assess somatotroph adenomas
- 24 hr urine cortisol levels to assess corticotroph adenomas
- thyrotropin-releasing hormone, TSH, free T3 and T4 levels to assess thyrotroph adenomas
