Posterior pituitary ectopia and hypopituitarism--magnetic resonance appearances of four cases and a review of the literature.

In four patients presenting in childhood with varying degrees of hypopituitarism, magnetic resonance imaging (MRI) showed a reduction in size of the normal pituitary fossa contents and an absent or very narrow stalk. A high signal intensity, enhancing area at the base of the stalk, having the appearances and signal characteristics of the posterior pituitary, was seen in each case. We discuss the case histories and MR findings in our patients and review the relevant literature.