Autopsy reports and radiologic and MRI evidence from around the globe indicate that one out of every five people worldwide has a pituitary tumor. The earliest study took place in 1936, when Dr. R.T. Costello of the Mayo Foundation conducted a cadaver study and found pituitary tumors in 22.4 % of the population (Costello R.T. Subclinical adenoma of the pituitary gland. Am. J. Pathol. 1936; 12:205-214). Statistics have not changed much ever since. The clinical significance of these findings are critical to determine.