Non-functional pituitary adenoma is a highly heterogeneous neoplasm with different origin of cells and multiple hormone-expressed subtypes, including intact gonadotroph with LH/FSH+ (40–79%), silent somatotroph with GH expression (3%), silent corticotroph with ACTH expression (8%), null cell without hormone expression (17%), and oncocytoma without hormone expression (6%) (3, 37, 38). The gene discussed is PLOD1; the disease is oncocytic adenoma.