Benign tumour derived from cells of anterior pituitary

Aetiology

• Sporadic or associated with MEN1

Pathophysiology

Micro-adenomas

• Adenomas <1cm
• Much less aggressive than macroadenomas

Macroadenomas

• Adenomas >1cm
• Can present with visual field defects due to compression of the optic chiasma
• Can cause pressure atrophy of normal surrounding cell tissue
• Infarction can lead to panhypopituitarism

Aggressive lesions

• A subset of adenomas behave aggressively and enlarge more rapidly (but don't metastasise as still benign)
• Features which indicate an aggressive lesion include lots of mitotic figures and p53 mutations

Pituitary carcinoma

• Rare, account for <1% of pituitary tumours
• Often functional (prolactin or ACTH usually)
• Metastasise late after multiple recurrences

Clinical features