MGMT and pituitary gland adenoma: Because the low activity of MGMT, defined as <5% nuclear MGMT staining [15], is generally regarded as a predictive marker of sensibility and a favorable clinical outcome in patients with temozolomide-treated aggressive pituitary adenomas [15, 22, 27, 28], we have postulated that the assessment of MGMT immunoexpression should be a standard component of a postsurgical specimen study in patients after a second adenomectomy because of suspecting the atypical adenoma.