Pituitary Acrogigantism: From the Past to the Future.

Pituitary acrogigantism is a very rare disease that is caused by chronic growth hormone (GH) axis excess that begins during childhood and adolescence. As such, it represents one of the most severe manifestations of acromegaly. In most cases, acrogigantism is caused by a pituitary adenoma, but hyperplasia can also accompany the adenoma or rarely occur alone. Individual cases of pituitary acrogigantism due to peripheral neuroendocrine tumor-derived GH-secreting hormone excess that stimulates pituitary GH hypersecretion have been reported. About half of patients with pituitary acrogigantism carry an identifiable germline genetic alteration (pathogenic variants, copy number variations, alterations of topologically associated domains (TADs), mosaicism), making it one of the most genetically-determined endocrine tumors. Among the genetic causes, pathogenic variants in the AIP gene (30%), the TADopathy X-linked acrogigantism (10%), and McCune-Albright syndrome (5%) are the most frequent causes. Molecular alterations induced by these genetic and genomic changes lead to large aggressive somatotropinomas that occur at an early age, secrete abundant amounts of GH, and produce treatment-resistant increases in insulin-like growth factor 1. X-linked acrogigantism occurs in the first year of life and is usually present by the age of 36 months, whereas, McCune-Albright syndrome-related GH excess usually presents before 5 years of age. AIP-related pituitary acrogigantism has a median age at diagnosis of about 16 years of age. Patients with pituitary acrogigantism have a heavy burden of disease and a complex treatment journey; the need to control final height makes it imperative to provide a diagnosis and effective hormonal control as rapidly as possible. Multimodal therapy is often required, and this can be complicated by the need for medical therapies that are not labeled for use in the pediatric population.