[Two cases of lymphocytic infundibuloneurohypophysitis].

We report two cases of lymphocytic infundibuloneurohypophysitis (LIH). A 32-year-old male and a 13-year-old male were admitted to our hospital because of a sudden occurrence of the diabetes insipidus (DI). MRI of both patients showed the disappearance of hyperintensity of the posterior pituitary in T1WI, pituitary stalk swelling and enlargement of the pituitary gland, with homogeneous enhancement by gadolinium. We thereby diagnosed LIH, so neither patient was operated on, but both were followed-up conservatively. We reviewed 51 cases of LIH. The patient's ages ranged from 4 to 74 years (mean 45.4 years). Based on the initial symptoms, DI was found in all cases. Almost all these cases revealed characteristic MRI findings similar to those in our cases. The mean follow-up period was 3.1 years. The rate of disappearance of radiological abnormalities was 56.2%, but only 13.7% of DI improved. If we encounter a patient presenting with idiopathic DI whose MRI is strongly suggestive of LIH, and barring the necessity of an urgent operation, careful conservative treatment is advised.