Molecular and immunohistochemical analysis is performed to demonstrate lineage-specific transcription factor expression (e.g., Pit-1, SF-1, and T-Pit) and mutation profiling consistent with pituitary adenoma subtypes as well as strong positivity for pituitary hormones (including GNAs in GH-secreting tumors and USP8 in corticotroph adenomas), confirming its monoclonal nature and distinguishing it from the craniopharyngioma component. Here, GNAS is linked to ACTH-producing pituitary gland adenoma.