Infundibulohypophysitis is an unusual inflammatory condition that affects the infundibulum, the pituitary stalk and the neurohypophisis and may be a part of a range that includes lymphocityc hypophysitis. It occurs mainly in women and most often presents in later stages of pregnancy. Infundibilohypophysitis usually presents with diabetes insipidus. The case of a 30-year-old woman with diabetus insipidus diagnosticated in the third trimester of the pregnancy is reported. She was still taking synthetic ADH 3 years after delivery. Evaluated in our service we found a polydipsia-polyuria syndrome (10 liters without treatment, urine density 1002), that does not respond to water deprivation test and respond to ADH administration. Sarcoidosis was excluded but the antecedents of tuberculosis and uncertain tuberculin test did not exclude a cerebral tuberculosis lesion and the diagnostic was kept in mind. Magnetic resonance imaging in these patient reveal thickening of the pituitary stalk, loss of hyperintense signal of the posterior pituitary and an adenohypophysis of normal size. After three month of corticotherapy (beginning with Prednisone 100 mg/day, 2 weeks with progressive lowering of the dose) the polyuro-polydipsic syndrome without treatment regress at 70 000 ml/day, the necessary dose of synthetic ADH dose decrease at 0.2 mg/day and the IRM imagining reveals a half reduction of pituitary stalk in all diameters. No reactivation of tuberculosis was noted after corticoids.
Conclusions: Diabetes insipidus with enlargement of pituitary stalk, with favorable evolution after glucocorticoid treatment is suggestive for infundibulohypophysitis; many of so called, idiopathic DI in the past have probably autoimmune ethyology. For diagnosis a suggestive IRM imaging±pituitary biopsy±vasopressin-cell antibodies are necessary. A prolonged follow-up of these patients is mandatory since other autoimmune diseases can occur later.