By definition, pituitary macroadenomas are benign tumors of the pituitary gland that are greater than 10 mm in diameter. Similar to microadenomas, macroadenomas may come to medical attention due to signs and symptoms of endocrine dysfunction from excessive hormonal production. However, in contrast to microadenomas, macroadenomas may result in reduced hormone production of some or all of the pituitary hormones (panhypopituitarism) as the tumor grows and compresses the normal pituitary tissue. Macroadenomas may also result in focal neurological signs and symptoms due to mass effect as the tumor grows outside of the sella and compresses the optic chiasm and hypothalamus above. Lesions of the optic chiasm classically result in a bitemporal hemianopsia.