prolactinoma Flashcards
definition of prolactinoma
benign lactotroph adenomas expressing and secreting prolactin
epidemiology of prolactinoma
most common type of pit adenoma
more in women, mainly in hcild bearing years 20-30s
sex imbalance not apparent >50yrs
aetiology of prolactinomas
monoclonal - arise from the proliferation of single mutated pit cells, somatic cell mutations stimulate cellular growth rate
occur sporadiacally
may have MEN1 or familial isolated pit adenoma (FIPA)
in FIPA patients - prolactinomas associated with aryl hydrocarbon receptor-interacting protein (AIP) gene mutations were large, occurred at a young age (<30 years), were invasive, had suprasellar extension and were resistant to dopamine agonist treatment
Consideration should be given to screening young patients (<40 years) presenting with large prolactinomas for AIP gene mutations and MEN-1
pathophysiology of prolactinomas
anterior pituitary lactotroph tumours
hypersecretion of prolactin causes secondary hypogonadism because of inhib effect on gonadotrophin releasing hormone and pit gonadotrophins
Dopamine is transported from the hypothalamus to the anterior pituitary by hypophysial portal vessels where it inhibits prolactin secretion via dopamine receptors expressed by lactotrophs –> disruption of dopamine secretion or transport to the portal vessels can = hyperprolactinaemia.
micro-adenomas
Small, intrasellar tumours, <10 mm in diameter
Rarely increase in size
Most common type in women.
macro adenomas
Larger tumours, >10 mm in diameter
Usually locally invasive into the suprasellar or parasellar regions
Sometimes associated with aggressive compression of vital structures
Men and post-menopausal women more commonly present with large and invasive adenomas, occasionally giant tumours (4 cm or greater)
Almost invariably benign (malignant prolactinomas that metastasise outside the pituitary sella are very rare).
signs and symptoms of prolactinoma
amenorrhoea or oligomenorrhoea
infertility - high prolactin inhibits ovulation
galactorrhoea - sign
loss of libido
erectile dysfunction
temporal hemianopia
osteoporosis
increased weight
dry vagina
men - reduced facial hair
present late with local pressure effects from tumour
investigations for prolactinoma
elevated serum prolactin - collected at any time in the day, non-stressful venepuncture
preg test
TFTs
UE
MRI pit - characteristic features of pit adenoma
computerised visual field exam - unilateral or bitemporal hemianopia
1st line management of prolactinomas
dopamine agonist (bromocriptine or cabergoline)
treatment of microprolactinomas
bromocriptine (dopamine agonist) reduces PRL secretion, restore menstrual cycles and reduces tumour size
dose is titrated up 1.25mg PO - increase weekly by 1.25-2.5mg/d until 2.5mg/12hr
SE - nausea, depression, postural hypotension (minimise by giving at night)
if preg planned use barrier contraception until 2 periods have occured
if subsequent preg - stop bromocriptine once 1st period missed
cabergoline is more effective and has fewer SE, but less data in preg
ergot alkaloids (ie bromocriptine and cabergoline) can cause fibrosis - echo needed
trans-sphenoidal surgey considered if intolarant of med - high success rate put risks of perm hormone deficiency and prolactinoma recurrence - so 2nd line
treatment of macroprolactinomas
near optic chiasm so may be reduced acuity, diplopia, opthalmoplegia, visual field loss and optic atrophy
treat with dopamine agonist (bromocriptine if fertility is the goal)
surgery rare - if visual symptoms or pressure effects which fail to respond to med
bromocriptine and in some cases radiation may be needed post op as complete resection uncommon
in preg monitor closely in antenatal and endo clinic as increased risk of expansion
follow up for prolactinoma treatment
monitor PRL
if headache or visual loss - check fields and MRI
med can be decreased after 2yrs, but recurrence of hyperprolactinaemia and expansion of tumour may occur so monitor carefully
complications of prolactinoma
visual field impairment
anterior pit failure/DI
hypopit from radiotherapy
cabergoline associated valvular insufficiency
pit apoplexy
cerebrospinal fluid leakage
prognosis of prolactinoma
progressive improving course while medically treated
treatment will = prolactin normalisation, tumour shrinkage or disappearance and rapid visual improvement
