Craniopharyngioma is a type of benign brain tumor that develops from embryonic tissue that forms part of the pituitary gland. While technically benign, its location makes it dangersous none-the-less. Pressure on the pituitary by the tumor reduces the availability of the hormone vasopressin and raises the pressure within the cranium. A craniopharyngioma usually includes hard, calcified components within the tumor itself, and disrupts normal skull development in its vicinity. Treatment is usually surgical.