For how long does it take for a pituitary adenoma to grow 2 cm?

Macroadenoma. If a 2 cm pituitary adenoma is discovered, it is likely that it has been there and growing for years, perhaps 10 yr, but it depends on what kind of tumor, whether it is secreting anything, what symptoms you have. For example, if you are a woman, and the tumor is a prolactinoma, you may be able to date the onset of tumor growth to the cessation of your periods.