Overgrowth in childhood is one of the symptoms of gigantism and acromegaly. Gigantism is generally an endocrine metabolic disease caused by persistent overproduction of growth hormone (GH). The main cause of GH overproduction is pituitary GH tumors or hyperplasia of pituitary GH cells, but the etiology of the tumors or hyperplasia is not known. If the growth hormone secretion is insufficient in early childhood, pituitary dwarfism will occur; on the contrary, if the secretion is excessive, those who start to suffer from adolescence will be gigantism, those who start to suffer from adulthood will be acromegaly, and those who start to suffer from pre-adulthood and post-adulthood will be gigantism-acromegaly. The etiology of overgrowth in childhood has two main points. 1. Pituitary: accounts for the vast majority. Including GH cell hyperplasia or adenoma, GH/PRL cell mixed adenoma, lactogenic growth hormone cell adenoma, eosinophilic stem cell adenoma and so on. Extrapituitary: heterogeneous GH/and or GHRH-secreting tumors (lung, pancreatic adenocarcinoma, hypothalamic malignancy, carcinoid tumors, pancreatic islet cell tumors). These tumors are often life-threatening before the clinical manifestations of GH hypersecretion.