A tumor of the pituitary gland that is a centimeter or greater in diameter. Some macroadenomata secrete excessive quantities of hormones (e.g., adrenocorticotropic hormone, prolactin, or growth hormone). Growth of the tumor mayalso cause damage to the sella turcica or impinge on the optic chiasm or cranial nerves. Symptoms of macroadenomata vary but include headaches, visual field deficits, galactorrhea, acromegaly, or Cushing’s disease. The tumors may be treated medically or surgically.