Somatotroph Cell Adenomas 	

Approximately fifteen per cent of pituitary tumours are usually associated with gigantism before epiphysial fusion or acromegaly after epiphysial fusion. Acromegaly is the more common manifestation since pituitary tumours occur most frequently in middle age and only rarely in childhood. Large tumours or macroadenomas, particularly those secreting prolactin and GH, are often locally invasive, rendering complete surgical removal difficult or impossible. Many pituitary tumours have mixed cell populations; for example, somatotroph and lactotroph cells are associated with increased secretion of both GH and prolactin. With mixed-cell tumours, however, the same cell is only rarely found to contain both hormones.