Spontaneously Resolving Lymphocytic Hypophysitis as a Cause of Postpartum Diabetes Insipidus

Abstract

A previously healthy 34-year-old woman developed diabetes insipidus 5 months after an uncomplicated pregnancy and delivery. MRI showed marked thickening of the pituitary stalk and prominence of the median eminence of the hypothalamus, with a somewhat small anterior pituitary gland. Further endocrine testing documented mild hyperprolactinemia and evidence of Hashimoto's disease (elevated TSH and an elevated titer of antimicrosomal antibodies). The radiographic abnormalities resolved spontaneously over the next 3 months, leaving a partially empty sella turcica. The prolactin level also normalized, but diabetes insipidus persisted. Although die diagnosis was not biopsy-proven, this case has a number of features mat are typical of lymphocytic hypophysitis (which are discussed); however, unlike the typical presentation of lymphocytic hypophysitis (in which anterior pituitary involvement is prominent, usually as a pituitary mass with anterior pituitary hypofunction), this case is unusual in its presentation with diabetes insipidus and in the localization of radiographic abnormalities to the pituitary stalk and hypothalamus. These features expand and further define die spectrum of die clinical presentation of lymphocytic hypophysitis. This patient's course confirms die recent observations of others that die natural history of this disorder may be that of a self-limiting disease with spontaneous resolution. As a result, die risks associated with confirmation of die diagnosis by biopsy (or surgical resection of involved tissue) are unnecessary and inappropriate if die clinical presentation is consistent with lymphocytic hypophysitis, and if subsequent follow-up demonstrates die anticipated radiographic normalization (as seen here and in other cases). Empty sella syndrome may represent die end stage of lymphocytic hypophysitis in some patients.