Surgical pathology examination and immunohistochemistry of the sellar mass from case 1. A, Hematoxylin and eosin stain of the pituitary adenoma, 200×. B, Many cells contain Crooke's hyaline around the nucleus, 400×. C, T-PIT transcription factor immunohistochemical stain confirms corticotroph lineage, 200×. D, Adrenocorticotropin (ACTH) immunohistochemical stain showing many cells are positive for ACTH and have peripheral accentuation of the stain with negativity around the nucleus supporting the presence of Crooke's hyaline (arrows), 200×.