Pituitary tumors are divided into microadenomas, macroadenomas, and macroadenomas according to size. Microadenomas are defined as pituitary tumors less than or equal to 1 cm in diameter; macroadenomas are defined as pituitary tumors greater than 1 cm in diameter; and adenomas larger than 4 cm in diameter are called macroadenomas. The purpose of clinical staging of pituitary size is to assess the level of endocrine hormone abnormality involved, primarily based on the size of the pituitary gland. In addition, the size of the pituitary tumor needs to be evaluated in terms of whether it is exerting pressure on the surrounding tissues and organs. Again, it is important to properly evaluate the size of the pituitary tumor with the goal of better guiding the next surgical treatment plan. Microadenomas are often resolved with transsphenoidal surgery, while macroadenomas and macroadenomas often require open surgery.