Pituitary tumours Flashcards
What would a pituitary tumour of somatotrophs cause?
Acromegaly
What would a pituitary tumour of lactotroph cells be called?
Prolactinoma
What would a pituitary tumour of thyrotrophs be called?
TSHoma
What would a pituitary tumour of gonadotrophs be called?
Gonadotrophinoma
What would a tumour of corticotrophs be called?
Cushing’s Disease
What are the three classifications for Pituitary tumours?
Radiological (MRI)
Function
Benign or Malignant
What is determined from the MRI of a pituitary tumour?
- Size Microadenoma <1cm (10mm) Macroadenoma >1cm (10mm) - Sellar or suprasellar - Compressing optic chiasm or not - Invading cavernous sinus or not ( very hard to remove surgically from the cavernous sinus)
What are the functional classifications for a pituitary tumour?
Excess secretion of a specific pituitary hormone
eg prolactinoma
No excess secretion of pituitary hormone (Non Functioning Adenoma)
Are pituitary tumours more likely to be benign or malignant?
Pituitary carcinoma very rare (<0.5% of pituitary tumours)
Mitotic index measured using Ki67 index – benign is <3%
Pituitary adenomas can have benign histology but display malignant behaviour
How does hyperprolactinaemia inhibit kisspeptin neurons?
Prolactin binds to prolactin receptors on kisspeptin neurons in hypothalamus
Inhibits kisspeptin release.
Decreases in downstream GnRH/LH/FSH/T/Oest
Oligo-amenorrhoea/Low libido/Infertility/Osteoporosis
What is the commonest functioning pituitary adenoma?
Commonest functioning pituitary adenoma
Usually serum [prolactin] >5000 mU/L
Serum prolactin is proportional to tumour size
What is the presentation for Prolactinomas?
Menstrual disturbance Erectile dysfunction Reduced libido Galactorrhoea ( very rare in men) Subfertility
What are other causes of elevated prolactin?
Physiological; - Pregnancy/breastfeeding - Stress: exercise, seizure, venepuncture - Nipple/chest wall stimulation Pathological; - Primary hypothyroidism - Polycystic ovarian syndrome - Chronic renal failure Iatrogenic; - Antipsychotics - Selective serotonin re-uptake inhibitors - Anti-emetics - High dose oestrogen - Opiates
What questions would we ask ourselves if we saw someone with an elevated prolactin?
is this a true elevation in serum prolactin?
Prolactin has no diurnal variation, not affected by food.
Red flag would be high serum prolactin with no clinical features.
What would be the 3 possible options if you had a patient with raised prolactin but no clinical features?
False positive
Macroprolactin
Stress of venipuncture