GHRH and neuroendocrine neoplasm: Other (extremely) rare causes of acromegaly are ectopic GH excess, produced by tumours other than pituitary adenomas (e.g., lymphomas and pancreatic islet cell tumours), as well as growth hormone-releasing hormone (GHRH) excess, secondary to lesions of the central nervous system (e.g., hypothalamic hamartomas, choristomas, and ganglioneuromas), or neuroendocrine neoplasms (e.g., carcinoid tumours and small cell lung cancers) [1].