Thickened pituitary stalk with central diabetes insipidus: report of three cases.

Diabetes insipidus of central origin usually results from lesions in the hypothalamic neurohypophyseal system. Lymphocytic infundibuloneurohypophysitis is an uncommon cause. Cases of lymphocytic infundibuloneurohypophysitis with thickening of the pituitary stalk and enlargement of the neurohypophysis with no hyperintense signal in the posterior pituitary have been reported. Reported cases presenting with isolated thickening of the pituitary stalk are very rare. We report three such cases, one in a nulliparous woman and the other two in men. Magnetic resonance (MR) imaging in these patients revealed isolated thickening of the pituitary stalk, loss of the hyperintense signal of the posterior pituitary, and an adenohypophysis of normal size. All cases had abnormal nodular infundibular enlargement. One male patient had hypogonadism; the other patients showed no sign of adenohypophyseal deficiency on stimulation test. Serial follow-up MR imaging revealed that all three patients had persistent thickening of the pituitary stalk. Diabetes insipidus was controlled by the administration of desmopressin acetate in all patients.