Pituitary adenoma could be divided by size:
microadenomas (up to 10 mm),
macroadenomas (more then 10 mm),
giant pituitary adenomas (40 mm and more).
Hormones secreted include:
Pituitary adenomas present either due to hormonal imbalance (both microadenomas and macroadenomas) or mass effect on adjacent structures (macroadenomas), classically the optic chiasm. Rarely presentation can be catastrophic, due to pituitary apoplexy.
The most commonly employed approach to pituitary masses is endonasal, whereby the floor of the pituitary fossa is accessed via the nasal cavity. In large tumors, other approaches may be necessary.