Pituitary adenoma

Pituitary adenomas account for between 5% and 10% of intracranial tumours and present as a result of their endocrine effects or because of the compression of the visual pathways.

An asymmetric tumour growth may lead to predominantly uniocular visual loss due to optic nerve involvement, with a minor field loss in the other eye - often upper temporal.

Pituitary microadenomas may be associated with headache and may ultimately expand to cause chiasmal compression.

Approximately half of patients diagnosed with pituitary adenomas have microadenomas (<10 mm in size) and half have macroadenomas (≥10 mm).

Pituitary adenomas are classified as functioning (70%) or nonfunctioning (30%):

• Functioning pituitary adenomas
  • approximately 50% of functioning pituitary adenomas produce excess prolactin
    • possible clinical features associated with hyperprolactinaemia include:
      • amenorrhoea
      • female infertility
      • vaginal dryness
      • low male libido
      • low male testosterone levels, and erectile dysfunction
  • pituitary adenomas can result in increased production of growth hormone resulting in acromegaly
  • pituitary adenomas can cause hypercorticalism (Cushing's syndrome)
  • pituitary adenomas with excess secretion of thyrotropin can result in hyperthyroidism

Nonfunctioning pituitary adenomas produce clinical features as a result of growth and compression of neighbouring structures e.g. compression of the optic chiasm.

Reference:

• Tritos NA, Miller KK. Diagnosis and management of pituitary adenomas: a review. JAMA. 2023;329(16):1386-1398.