Pituitary stalk interruption syndrome

Pituitary stalk interruption syndrome, abbreviated PSIS, is a congenital disorder of the pituitary gland defined by a triad of findings: an absent or exceedingly thin pituitary stalk, an ectopic or absent posterior pituitary, and an absent or underdeveloped anterior pituitary. It is a common cause of congenital hypopituitarism and produces a permanent deficiency of growth hormone. Newborns may show low blood sugar and prolonged jaundice, while later childhood features include short stature, seizures, low blood pressure and delayed puberty. It can occur on its own or together with malformations outside the pituitary. The cause is not yet known; rare genetic mutations may explain familial cases, but these account for under five percent. The diagnosis is confirmed by MRI. Treatment begins as soon as the diagnosis is made and consists of hormone replacement, particularly with growth hormone. Prognosis is generally good with prompt treatment, though illness and death are more frequent than in the general population, especially in the first two years of life. About 1,000 cases have been reported, with or without the full triad.