MKI67 and pituitary gland adenoma: The criteria for diagnosing refractory pituitary adenomas are as follows: 1) tumor infiltrates adjacent structures according to radiological results or intraoperative findings; 2) tumor Ki-67 index is greater than 3% and growth velocity is more than 2% monthly; 3) current treatments fail to control tumor growth and/or hormonal hypersecretion; 4) tumor recurrence occurs within 6 months after surgery.