Expression of chorionic gonadotrophin in human pituitary adenomas.

In addition to the classical anterior pituitary hormones, many human pituitary adenomas express hormone genes ectopically. Expression of glycoprotein hormone α-subunit and, less commonly, free luteinizing hormone β (LH-β) or follicle-stimulating hormone β is characteristic of endocrinologically inactive adenomas, a subgroup thought to be derived predominantly from the gonadotroph line. Thyrotrophin β expression in these tumours is unusual, and specific chorionic gonadotrophin β (CG-β) expression, identified using oligonucleotide probes that reliably distinguish LH-β and CG-β in situ, is not well described