POU1F1 and ACTH-producing pituitary gland adenoma: Immunohistochemistry staining can be used for many types of tropic hormones, of which the most common type is silent gonadotropic adenoma, which accounts for 80% of resected nonfunctioning pituitary adenomas, followed by corticotropic adenoma, pituitary transcription factor-1 (GH/prolactin/TSH) lineage, then null cell adenoma.