Pituitary adenoma

Pituitary adenoma

A pituitary adenoma is a benign tumour of the pituitary gland. They are common (10% of all people) but in most cases will never be found (asymptomatic) or are found as an incidental findings. They account for around 10% of adult brain tumours.

Pituitary adenomas can be classified according to:

• size (a microadenoma is <1cm
  a microadenoma is <1cm
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  and a macroadenoma is ≥1cm)
• hormonal status (a secretory/functioning adenoma produces an excess of a particular hormone and a non-secretory/functioning adenoma does not produce a hormone to excess)

Prolactinomas are the most common type and they produce an excess of prolactin. After prolactinomas, non-secreting adenomas are the next most common, then GH-secreting and then ACTH-secreting adenomas.

Pituitary adenomas typically cause symptoms by:

• 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
  The presence of an elevated prolactin level along with secondary hypothyroidism and hypogonadism is indicative of stalk compression is consistent with a non-functioning pituitary adenoma
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  Importance: 84
  )
  • non-functioning tumours, therefore, present with generalised hypopituitarism
    Non-functioning pituitary tumours present with hypopituitarism and pressure effects
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    Importance: 58
• stretching of the dura within/around the pituitary fossa (causing headaches)
• compression of the optic chiasm (causing a bitemporal hemianopia
  bitemporal hemianopia
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  due to crossing nasal fibers)

Alternatively, pituitary adenomas, particularly microadenomas, can be an incidental finding on neuroimaging and therefore called a 'pituitary incidentaloma'.

Investigation requires:

• a pituitary blood profile (including GH, prolactin, ACTH, FSH, LSH and TFTs)
  a pituitary blood profile (including GH, prolactin, ACTH, FSH, LSH and TFTs)
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• formal visual field testing
• MRI brain with contrast

Differential diagnoses include:

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

Treatment may include a combination of

• medical therapy:
  • prolactinomas are generally treated first-line with dopamine agonists (e.g., cabergoline or bromocriptine).
  • somatostatin analogues (e.g., octreotide, lanreotide) and GH receptor antagonists (e.g., pegvisomant) are used for GH-secreting adenomas
  • for ACTH-secreting adenomas, medical therapy may include cortisol synthesis inhibitors (e.g., ketoconazole, metyrapone) and neuromodulators like pasireotide
• transsphenoidal surgery
  • the primary treatment for most pituitary adenomas is transsphenoidal surgery, especially for non-functioning and ACTH- or GH-secreting adenomas
  • surgical intervention aims to remove the tumour mass, normalise hormone levels, and
  • non-functioning adenomas are generally diagnosed due to their compressive symptoms (e.g. visual problems) or hormone deficiencies - surgery is therefore the first-line treatment
    Non-functioning adenomas are generally diagnosed due to their compressive symptoms (e.g. visual problems) or hormone deficiencies - transsphenoidal surgery is therefore the first-line treatment
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    Importance: 77
• radiotherapy
  • indicated for residual or recurrent tumours post-surgery

+PassMedicine Notes

A pituitary adenoma is a benign tumour of the pituitary gland. They are common (10% of all people) but in most cases will never be found (asymptomatic) or are found as an incidental findings. They account for around 10% of adult brain tumours.

Pituitary adenomas can be classified according to:

• size (a microadenoma is