Aetiology of Acromegaly-Associated Pituitary Tumours	

In some patients with acromegaly, somatotroph hyperplasia may occur because of excessive secretion of GHRH from a hypothalamic hamartoma (a tumour-like lesion, usually present at birth, which ceases to grow when general body growth ceases), hypothalamic gangliocytoma (a tumour of mature gangliocytes), or carcinoid tumour of the lung or pancreas. However, over ninety-nine per cent of patients have a primary pituitary tumour. Genetic factors may play a role in some tumours, such as in multiple endocrine neoplasia (MEN) syndrome type 1, where GH-secreting adenomas may constitute one of the neoplastic components.