Non-functioning pituitary adenoma

A rare pituitary tumor originating from normally hormone-producing cells of the adenohypophysis, characterized by a sellar or suprasellar mass manifesting with clinical signs secondary to mass effect, but without evidence for hormonal hypersecretion. Typical manifestations are visual disturbances, headaches, cranial nerve dysfunction, and hypopituitarism. Histologically, different subtypes can be distinguished based on the expression of anterior pituitary hormones and transcription factors, silent gonadotroph adenoma being the most common subtype, while non-expressing null cell adenomas are very rare. Assessment of tumor cell proliferation is important to identify potentially aggressive tumors.