Microadenoma is tumors less than 10 mm.
Macroadenoma includes tumors larger than 10mm. Giant pituitary neuroendocrine tumors are more than 40 mm. There are functional pituitary neuroendocrine tumors in which the cell type that composes them causes increased secretion of one or multiple hormones of the anterior pituitary. Alternatively, there are Non-Functioning Pituitary Neuroendocrine Tumors that do not secrete hormones, but they can compress the surrounding areas of the anterior pituitary leading to hormonal deficiencies 1).