Pituitary Adenoma

Question 1

What is it?

Answer 1

derived from cells of anterior pituitary
relatively common (10% intra-cranial tumours)
can be sporadic or associated with MEN1 (Wermer syndrome)
micro-adenoma <1cm, macro-adenomas >1cm

Question 2

how are they classified?

Answer 2

by cell type/ hormone produced 
- prolactin (20-30%)
- ACTH (10-15%)
- FSH/LH (10-15%)
- GH (5%)
can produce more than one 
can be hypo/ non-functional (25-30%) - later presentation, hormone production may be subclinical levels

Question 3

how does it present?

Answer 3

large adenomas
- visual field defects
- can cause pressure atrophy of surrounding normal tissue
- infarction can lead to panhypopituitarism
subset behave aggressively
- mitotic figures ++ and p53 mutations

Question 4

what are the ways that hormone producing tumours can act?

Answer 4

prolactinoma
- most common functional tumour (30%)
- infertility, lack of libido, amenorrhoea (25% amenorrhoea)
growth hormone secreting
- second most common
- GH causes increase in insulin like growth factors (IGF)
- stimulates growth of bone, cartilage and connective tissue
- gigantism and acromegaly
ACTH secreting
- Cushing’s disease - wide range of signs and symptoms
- usually microadenoma
- bilateral adrenocortical hyperplasia

Question 5

how common are pituitary carcinomas?

Answer 5

rare <1% pituitary tumours
often functional - prolactin or ACTH usually
metastasise late after multiple recurrences