Genetic basis of endocrine disease: pituitary tumor pathogenesis.

Pituitary tumors are mostly benign monoclonal adenomas arising from adenohypophyseal cells in the anterior pituitary. These tumors usually autonomously express and secrete pituitary hormones, leading to endocrinological syndromes, such as hyperprolactinemia (most common), acromegaly, Cushing’s disease, and, rarely, hyperthyroidism. Alternatively, they may be functionally silent and initially diagnosed as an expanding sellar mass resulting in hypopituitarism, usually with central hypogonadism, visual field defects, or headaches. Although our understanding of subcellular mechanisms for the pathogenesis and progression of these common tumors is incomplete, during recent years important new information on the role of intrinsic pituitary genetic alterations, disordered transcription factors and growth factors, and signaling proteins involved in pituitary tumorigenesis has been reported in both sporadic and hereditary adenomas (Table 1).