Pituitary tumours

Question 1

Are most pituitary adenomas benign or malignant?

Answer 1

almost always benign adenomas

account for 10% of intracranial tumours

Question 2

May be divided by size?

Answer 2

Microadenoma <1cm across

Macroadenoma is >1cm

Question 3

3 histological types of pituitary tumour?

Answer 3

1. chromophobe (70%): many are non-secretory, some cause hypopituitarism, half produce prolactin, a few prodcue ACTH or GH. local pressure effect 30%.
2. acidophil (15%): secrete GH or PRL. local pressure effect in 10%
3. basophil (15%): secrete ACTH. local pressure effect rare

Question 4

Most common type of pituitary adenoma?

Answer 4

Prolactinoma followed by non-secreting adenomas, then GH secreting and then ACTH secreting adenomas

Question 5

Pituitary adenomas typically cause symptoms by:

Answer 5

excess of a hormone (e.g. Cushing’s disease due to excess ACTH, acromegaly due to excess GH or amenorrhea and galactorrhea due to excess prolactin)

depletion of a hormone(s) (due to compression of the normal functioning pituitary gland)
- non-functioning tumours, therefore, present with generalised hypopituitarism

stretching of the dura within/around pituitary fossa (causing headaches)

compression of the optic chiasm (causing a bitemporal hemianopia due to crossing nasal fibers)

Question 6

pituitary adenomas, particularly microadenomas, can be an incidental finding on neuroimaging and therefore called?

Answer 6

a ‘pituitary incidentaloma’

Question 7

Investigation requires:

Answer 7

a pituitary blood profile (including: GH, prolactin, ACTH, FH, LSH and TFTs)

formal visual field testing

MRI brain with contrast

Question 8

Differential diagnoses include:

Answer 8

pituitary hyperplasia
craniopharyngioma
meningioma
brain metastases
lymphoma
hypophysitis
vascular malformation (e.g. aneurysm)

Question 9

Treatment may include a combination of:

Answer 9

hormonal therapy (e.g. bromocriptine is the first line treatment for prolactinomas)

surgery (e.g. transsphenoidal transnasal hypophysectomy)
e.g. if progression in size

radiotherapy

Question 10

What is a Craniopharyngioma?

Answer 10

not strictly a pituitary tumour: it originates from Rathke’s pouch so is situated between the pituitary and 3rd ventricle floor

They are rare, but the commonest childhood intracranial tumour

over 50% present in childhood with growth failure, adults may present with amenorrhoea, decreased libido, hypothalamic symptoms or tumour mass effect

TESTS: CT/MRI

Treatment: surgery with or without post-op radiation, test pituitary function post-op