PERSISTENT HIGH MR SIGNAL OF THE POSTERIOR PITUITARY-GLAND IN CENTRALDIABETES-INSIPIDUS

We describe three cases of central diabetes insipidus, each with a dif ferent pathogenesis, in which unexpected hyperintensity of the posteri or pituitary gland was seen on T1-weighted MR images obtained at the t ime of presentation, In the first case (idiopathic), the posterior pit uitary signal persisted more than 10 years; in the second case (Langer hans cell histiocytosis), the signal disappeared within 3 months, desp ite early specific chemotherapy with etoposide; and in the third case (transient), the posterior signal disappeared within 1 year, but it wa s documented at the time of spontaneous reversal of polyuria and polyd ipsia.