Acromegaly is caused by hyperplasia or adenomas of the growth hormone (GH) secreting cells of the pituitary gland, which results in excessive secretion of GH. Adolescents develop gigantism due to unclosed epiphyses; those with fused epiphyses develop acromegaly; and a few who start in puberty and continue to develop acromegalic gigantism as adults develop acromegalic gigantism. This disease is caused by pituitary tumors or other causes of excessive secretion of growth hormone from the pituitary gland, and there is a clear diurnal rhythm of GH secretion, with the peak of secretion in adults occurring at night. Excessive growth hormone mainly causes transitional growth of bones, soft tissues and internal organs, which is manifested as gigantism in adolescents and acromegaly in adults, with thickening of the skull, broadening of the head and face, high zygomatic bones, protruding jaws, sparse teeth and malocclusion, large arms and legs, hunchback, rough skin, increased hair, hyperpigmentation, hypertrophy of nose, lips and tongue, hypertrophy of vocal cords and low pitch and coarseness of the voice. Hypertrophy of the nose, lips and tongue, vocal folds, and low and coarse tone. Ectopic secretion of growth hormone is rare, and proliferation of pituitary GH cells due to excessive GHRH is common in carcinomatous tumors, and rare in hypothalamic malformations, gliomas and ganglion cell tumors.