SPONTANEOUSLY RESOLVING LYMPHOCYTIC HYPOPHYSITIS AS A CAUSE OF POSTPARTUM DIABETES-INSIPIDUS

A previously healthy 34-year-old woman developed diabetes insipidus 5 months after an uncomplicated pregnancy and delivery. MRI showed marke d thickening of the pituitary stalk and prominence of the median emine nce of the hypothalamus, with a somewhat small anterior pituitary glan d. Further endocrine testing documented mild hyperprolactinemia and ev idence of Hashimoto's disease (elevated TSH and an elevated titer of a ntimicrosomal antibodies). The radiographic abnormalities resolved spo ntaneously over the next 3 months, leaving a partially empty sella tur cica. The prolactin level also normalized, but diabetes insipidus pers isted. Although the diagnosis was not biopsy-proven, this case has a n umber of features that are typical of lymphocytic hypophysitis (which are discussed); however, unlike the typical presentation of lymphocyti c hypophysitis (in which anterior pituitary involvement is prominent, usually as a pituitary mass with anterior pituitary hypofunction), thi s case is unusual in its presentation with diabetes insipidus and in t he localization of radiographic abnormalities to die pituitary stalk a nd hypothalamus. These features expand and further define die spectrum of the clinical presentation of lymphocytic hypophysitis. This patien t's course confirms the recent observations of others that the natural history of this disorder may be that of a self-limiting disease with spontaneous resolution. As a result, the risks associated with confirm ation of the diagnosis by biopsy (or surgical resection of involved ti ssue) are unnecessary and inappropriate if the clinical presentation i s consistent with lymphocytic hypophysitis, and if subsequent follow-u p demonstrates the anticipated radiographic normalization (as seen her e and in other cases). Empty sella syndrome may represent the end stag e of lymphocytic hypophysitis in some patients.